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Search: id:A060945
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| A060945 |
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Number of ordered partitions of n into 1's, 2's and 4's. |
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+0
7
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| 1, 2, 3, 6, 10, 18, 31, 55, 96, 169, 296, 520, 912, 1601, 2809, 4930, 8651, 15182, 26642, 46754, 82047, 143983, 252672, 443409, 778128, 1365520
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,500
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FORMULA
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a(n) = a(n-1)+a(n-2)+a(n-4). G.f.: (x+x^2+x^4)/(1-x-x^2-x^4)
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PROGRAM
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(PARI) { for (n=1, 500, if (n>4, a=a1 + a2 + a4; a4=a3; a3=a2; a2=a1; a1=a, if (n==1, a=a4=1, if (n==2, a=a3=2, if (n==3, a=a2=3, a=a1=6)))); write("b060945.txt", n, " ", a); ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 15 2009]
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CROSSREFS
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Cf. A000045 (1's and 2's only), A023359 (all powers of 2)
Apart from n=0 term, same as unsigned version of A077930.
Sequence in context: A066067 A121364 A102702 this_sequence A077930 A023359 A082482
Adjacent sequences: A060942 A060943 A060944 this_sequence A060946 A060947 A060948
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KEYWORD
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nonn
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AUTHOR
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Len Smiley (smiley(AT)math.uaa.alaska.edu), May 07 2001
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