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Search: id:A025767
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| A025767 |
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Expansion of 1/((1-x)(1-x^3)(1-x^4)). |
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+0
2
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| 1, 1, 1, 2, 3, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 15, 17, 18, 20, 22, 24, 26, 28, 30, 33, 35, 37, 40, 43, 45, 48, 51, 54, 57, 60, 63, 67, 70, 73, 77, 81, 84, 88, 92, 96, 100, 104, 108, 113, 117, 121, 126, 131, 135, 140, 145, 150, 155, 160, 165, 171, 176, 181, 187, 193, 198
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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Apply the Riordan array (1/(1-x^4),x) to floor((n+3)/3). - Paul Barry (pbarry(AT)wit.ie), Jan 20 2006
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FORMULA
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G.f.: 1/((1-x)(1-x^3)(1-x^4)). a(n)=[n^2/24+n/3+1].
a(n)=sum{k=0..floor(n/4), floor((n-4k+3)/3)}; - Paul Barry (pbarry(AT)wit.ie), Jan 20 2006
Euler transform of length 4 sequence [ 1, 0, 1, 1]. - Michael Somos Nov 09 2007
a(-8 - n) = a(n). - Michael Somos Nov 09 2007
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PROGRAM
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(PARI) a(n)=if(n<0, 0, (n^2+8*n)\24+1)
(PARI) {a(n) = round( ((n + 4)^2 - 1) / 24 )} /* Michael Somos Nov 09 2007 */
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CROSSREFS
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A008621(n) = A002265(n+4) = a(n) - a(n-3).
Sequence in context: A011883 A034886 A011882 this_sequence A091848 A017886 A029038
Adjacent sequences: A025764 A025765 A025766 this_sequence A025768 A025769 A025770
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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