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A134153 a(n) = 15n^2 + 9n + 1. 11
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

A119617 is union of A134153 and A134154. A000538(n) is divisible 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)

LINKS

Table of n, a(n) for n=0..39.

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

FORMULA

(i) a(n) = 15n^2 + 9n + 1. (ii) a(n) = (3(5n + 1)^2 + 3 (5n + 1) - 1)/5. (iii) 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, Nov 14 2007

MATHEMATICA

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*)

PROG

(PARI) a(n)=15*n^2+9*n+1 \\ Charles R Greathouse IV, Jun 17 2017

CROSSREFS

Cf. A119617, A134154.

Sequence in context: A192504 A033658 A080699 * A251311 A223181 A016814

Adjacent sequences:  A134150 A134151 A134152 * A134154 A134155 A134156

KEYWORD

nonn,easy

AUTHOR

Artur Jasinski, Oct 10 2007

EXTENSIONS

Offset corrected and some punctuation added by R. J. Mathar, Jul 09 2009

STATUS

approved

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Last modified October 23 19:26 EDT 2021. Contains 348215 sequences. (Running on oeis4.)