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Search: id:A071919
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| A071919 |
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Number of monotone nondecreasing functions [n]->[m] for n>=0, m>=0, read by antidiagonals. |
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+0
6
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| 1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 3, 1, 0, 1, 4, 6, 4, 1, 0, 1, 5, 10, 10, 5, 1, 0, 1, 6, 15, 20, 15, 6, 1, 0, 1, 7, 21, 35, 35, 21, 7, 1, 0, 1, 8, 28, 56, 70, 56, 28, 8, 1, 0, 1, 9, 36, 84, 126, 126, 84, 36, 9, 1, 0, 1, 10, 45, 120, 210, 252, 210, 120, 45, 10, 1, 0, 1, 11, 55, 165, 330, 462
(list; table; graph; listen)
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OFFSET
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0,8
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COMMENT
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Sometimes called a Riordan array.
Number of different partial sums of 1+[2,3]+[3,4]+[4,5]+... - Jon Perry (perry(AT)globalnet.co.uk), Jan 01 2004
Triangle T(n,k), 0<=k<=n, read by rows, given by [1, 0, 0, 0, 0, 0, 0, 0, ...] DELTA [0, 1, 0, 0, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938 . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Sep 05 2005
T(n,k)=abs(A110555(n,k)), A110555(n,k)=T(n,k)*(-1)^k. - Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Jul 27 2005
(1,0)-Pascal triangle . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 21 2006
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REFERENCES
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D. Merlini, F. Uncini and M. C. Verri, A unified approach to the study of general and palindromic compositions, Integers 4 (2004), A23, 26 pp.
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FORMULA
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T(n, k)=1 if (n, k)=(0, 0), a(n, k)=binomial(n+k-1, n) otherwise. - Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Jul 27 2005
G.f.: 1 +x +x^3(1+x) +x^6(1+x)^2 +x^10(1+x)^3 +... . - Michael Somos Aug 20 2006
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PROGRAM
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(PARI) { n=20; v=vector(n); for (i=1, n, v[i]=vector(2^(i-1))); v[1][1]=1; for (i=2, n, k=length(v[i-1]); for (j=1, k, v[i][j]=v[i-1][j]+i; v[i][j+k]=v[i-1][j]+i+1)); c=vector(n); for (i=1, n, for (j=1, 2^(i-1), if (v[i][j]<=n, c[v[i][j]]++))); c } (Jon Perry)
(PARI) {a(n)=local(m); if(n<1, n==0, m=(sqrtint(8*n+1)-1)\2; binomial(m-1, n-m*(m+1)/2))} /* Michael Somos Aug 20 2006 */
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CROSSREFS
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Sequence in context: A077593 A119337 A110555 this_sequence A097805 A127839 A017827
Adjacent sequences: A071916 A071917 A071918 this_sequence A071920 A071921 A071922
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KEYWORD
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nonn,easy,tabl
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AUTHOR
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Michele Dondi (bik.mido(AT)tiscalinet.it), Jun 14, 2002
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EXTENSIONS
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More terms from Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Jul 27 2005
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