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Search: id:A145919
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| 0, 0, 0, 0, 1, 2, -3, 5, 7, -9, 12, 15, -18, 22, 26, -30, 35, 40, -45, 51, 57, -63, 70, 77, -84, 92, 100, -108, 117, 126, -135, 145, 155, -165, 176, 187, -198, 210, 222, -234, 247, 260, -273, 287, 301, -315, 330, 345, -360, 376, 392, -408, 425, 442, -459, 477
(list; graph; listen)
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OFFSET
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0,6
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COMMENT
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As the formula in the description shows, all members of A000332 belong to the generalized pentagonal sequence (A001318). A001318 also lists all nonnegative numbers that belong to A145919.
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LINKS
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Eric Weisstein's World of Mathematics, Pentagonal Number.
Eric Weisstein's World of Mathematics, Pentatope Number.
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FORMULA
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a(n+3)= A001840(n) when 3 does not divide n, A001840(n)*-1 otherwise.
After first two zeros, this sequence consists of all values of A001318(n) and A045943(n)*(-1), n>=0, sorted in order of increasing absolute value.
G.f.:(-x^4*(x^4+2*x^3-3*x^2+2*x+1))/((x-1)^3*(1+x^2+x)^3) [From Maksym Voznyy (voznyy(AT)mail.ru), Jul 27 2009]
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EXAMPLE
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a(6) = -3 and A000332(6) = (-3)(-10)/2 = 15.
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CROSSREFS
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Cf. A000326, A145920.
Sequence in context: A024195 A071423 A062781 this_sequence A058937 A130518 A001840
Adjacent sequences: A145916 A145917 A145918 this_sequence A145920 A145921 A145922
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KEYWORD
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easy,sign
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AUTHOR
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Matthew Vandermast (ghodges14(AT)comcast.net), Oct 28 2008
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