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A191012 a(n) = n^5 - n^4 + n^3 - n^2 + n. 1
0, 1, 22, 183, 820, 2605, 6666, 14707, 29128, 53145, 90910, 147631, 229692, 344773, 501970, 711915, 986896, 1340977, 1790118, 2352295, 3047620, 3898461, 4929562, 6168163, 7644120, 9390025, 11441326, 13836447, 16616908, 19827445 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

n such that x^5 + x^4 + x^3 + x^2 + x + n factors over the integers.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).

FORMULA

a(n) = n*A060884(n).

G.f.: x*(5*x^4 + 32*x^3 + 66*x^2 + 16*x + 1)/(1-x)^6.

EXAMPLE

a(2) = 22 is in the sequence, because x^5 + x^4 + x^3 + x^2 + x + 22 = (x+2)*(x^4 - x^3 + 3*x^2 - 5*x + 11).

MAPLE

[seq(n*(n^4-n^3+n^2-n+1), n=0..25)];

PROG

(PARI) a(n)=((((n-1)*n+1)*n-1)*n+1)*n \\ Charles R Greathouse IV, Jun 17 2011

(MAGMA) [n^5 - n^4 + n^3 - n^2 + n: n in [0..30]]; // Vincenzo Librandi, Jun 18 2011

CROSSREFS

Cf. A060884.

Sequence in context: A107969 A248489 A248490 * A248491 A248492 A248493

Adjacent sequences:  A191009 A191010 A191011 * A191013 A191014 A191015

KEYWORD

easy,nonn

AUTHOR

Franz Vrabec, Jun 16 2011

STATUS

approved

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Last modified October 17 00:35 EDT 2021. Contains 348048 sequences. (Running on oeis4.)