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Search: id:A134153
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| A134153 |
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a(n) = 15n^2 + 9n + 1. |
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+0
10
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| 1, 25, 79, 163, 277, 421, 595, 799, 1033, 1297, 1591, 1915, 2269, 2653, 3067, 3511, 3985, 4489, 5023, 5587, 6181, 6805, 7459, 8143, 8857, 9601, 10375, 11179, 12013, 12877, 13771, 14695, 15649, 16633, 17647, 18691, 19765, 20869, 22003, 23167
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OFFSET
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1,2
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COMMENT
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A119617 is union of A134153 and A134154 A000538(n) is divisable by A000330(n) if and only n is congruent to {1, 3} mod 5 (see A047219) A134154(n) is case when n is congruent to 1 mod 5 see cases 2)
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FORMULA
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1) a(n) = 15n^2 + 9n + 1 2) a(n) = (3(5n + 1)^2 + 3 (5n + 1) - 1)/5 3) a(n) = sum[k^4]/sum[k^2], {k, 1, 5m + 1}]
G.f.: -(1+22*x+7*x^2)/(-1+x)^3. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 14 2007
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MATHEMATICA
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1) Table[1 + 9 n + 15 n^2, {n, 0, 50}] 2) Table[Sum[k^4, {k, 1, 5m + 1}]/Sum[k^2, {k, 1, 5m + 1}], {m, 0, 10}] (*Artur Jasinski*)
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CROSSREFS
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Cf. A119617, A134154.
Sequence in context: A042230 A033658 A080699 this_sequence A016814 A100487 A069232
Adjacent sequences: A134150 A134151 A134152 this_sequence A134154 A134155 A134156
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Oct 10 2007
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