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

Offset: 1

Author

Philippe Deléham, Mar 09 2014

Keywords

• easy
• nonn

Comments

Row sums of A016755 read as triangular array.

Examples

			A016755, as triangular array begins:
1;
27, 125;
343, 729, 1331;
2197, 3375, 4913, 6859;
9261, 12167, 15625, 19683, 24389;
29791, 35937, 42875, 50653, 59319, 68921;..
Row sums are:
1;
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.
		

Links

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

Crossrefs

Cf. A016755.

Programs

Magma

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

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 *)

PARI

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

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.