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Search: id:A134154
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| A134154 |
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a(n) = 15n^2 - 9n + 1. |
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+0
10
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| 1, 7, 43, 109, 205, 331, 487, 673, 889, 1135, 1411, 1717, 2053, 2419, 2815, 3241, 3697, 4183, 4699, 5245, 5821, 6427, 7063, 7729, 8425, 9151, 9907, 10693, 11509, 12355, 13231, 14137, 15073, 16039, 17035, 18061, 19117, 20203, 21319, 22465, 23641
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OFFSET
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0,2
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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 3 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 + 3)^2 + 3 (5n + 3) - 1)/5 3) a(n) = sum[k^4]/sum[k^2], {k, 1, 5m + 3}]
G.f.: -(1+4*x+25*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 + 3}]/Sum[k^2, {k, 1, 5m + 3}], {m, 0, 30}] (*Artur Jasinski*)
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CROSSREFS
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Cf. A000538, A119617, A134153.
Sequence in context: A052029 A142102 A031914 this_sequence A114352 A112563 A027176
Adjacent sequences: A134151 A134152 A134153 this_sequence A134155 A134156 A134157
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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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