A239065 - OEIS

A239065

n^3*(n^4 + n^2 - 1).

1, 152, 2403, 17344, 81125, 287496, 840007, 2129408, 4841289, 10099000, 19646891, 36078912, 63117613, 105948584, 171615375, 269479936, 411753617, 614103768, 896340979, 1283192000, 1805163381, 2499500872, 3411249623, 4594420224, 6113265625, 8043673976

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OFFSET

1,2

COMMENTS

Row sums of A016755 read as triangular array.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = n^7 + n^5 - n^3.

G.f.: x*(1+144*x+1215*x^2+2320*x^3+1215*x^4+144*x^5+x^6)/(x-1)^8.

EXAMPLE

A016755, as triangular array begins:

27, 125;

343, 729, 1331;

2197, 3375, 4913, 6859;

9261, 12167, 15625, 19683, 24389;

29791, 35937, 42875, 50653, 59319, 68921;..

Row sums are:

3^3 + 5^3 = 27 + 125 = 152;

7^3 + 9^3 + 11^3 = 343 + 729 + 1331 = 2403;

13^3 + 15^3 + 17^3 + 19^3 = 2197 + 3375 + 4913 + 6859 = 17344;

21^3 + 23^3 + 25^3 + 27^3 + 29^3 = 9261 + 12167 + 15625 + 19683 + 24389 = 81125;

31^3 + 33^3 + 35^3 + 37^3 + 39^3 + 41^3 = 287496 = 66^3.

MAPLE

A239065:=n->n^7 + n^5 - n^3; seq(A239065(n), n=1..30); # Wesley Ivan Hurt, Mar 09 2014

MATHEMATICA

Table[n^7 + n^5 - n^3, {n, 30}] (* Wesley Ivan Hurt, Mar 09 2014 *)

CoefficientList[Series[(1 + 144 x + 1215 x^2 + 2320 x^3 + 1215 x^4 + 144 x^5 + x^6)/(x - 1)^8, {x, 0, 40}], x] (* Vincenzo Librandi, Mar 11 2014 *)

PROG

(PARI) a(n) = n^7+n^5-n^3 \\ Charles R Greathouse IV, Mar 09 2014

(Magma) [n^3*(n^4 + n^2 - 1): n in [1..30]]; // Vincenzo Librandi, Mar 11 2014

CROSSREFS

Cf. A016755.

Sequence in context: A364815 A359447 A223397 * A229418 A035823 A265861

Adjacent sequences: A239062 A239063 A239064 * A239066 A239067 A239068

KEYWORD

easy,nonn

AUTHOR

Philippe Deléham, Mar 09 2014

STATUS

approved