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Search: id:A087628
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| A087628 |
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Generalized Jacobsthal sequence. |
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+0
2
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| 1, 2, 2, 2, 10, 22, 22, 86, 170, 170, 682, 1366, 1366, 5462, 10922, 10922, 43690, 87382, 87382, 349526, 699050, 699050, 2796202, 5592406, 5592406, 22369622, 44739242, 44739242, 178956970, 357913942, 357913942, 1431655766, 2863311530
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n)=sum{k=0..n, if (mod(k(n-k), 3)=0, comb(n, k), 0) }; a(n)=if (mod(n, 3)=0, A0010045(n+1)-A001045(n), A001045(n+1)-(-1)^n).
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CROSSREFS
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Cf. A087629.
Sequence in context: A152681 A138674 A122946 this_sequence A089871 A068971 A019233
Adjacent sequences: A087625 A087626 A087627 this_sequence A087629 A087630 A087631
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Sep 14 2003
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