A123657 a(n) = 1 + n^4 + n^6 + n^9.

4, 593, 20494, 266497, 1969376, 10125649, 40473658, 134483969, 387958492, 1001010001, 2359733894, 5162787073, 10609354744, 20668614737, 38454800626, 68736319489, 118612097588, 198393407569, 322734873982, 512064160001

Offset: 1

Author

Jonathan Vos Post, Oct 04 2006

Keywords

• easy
• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (10,-45,120,-210,252,-210,120,-45,10,-1).

Crossrefs

Cf. A001358, A002523, A091940, A123177, A123656-A123659.

Programs

Magma

[1 + n^4 + n^6 + n^9: n in [1..25]]; // G. C. Greubel, Oct 17 2017

Mathematica

Table[1 + n^4 + n^6 + n^9, {n, 1, 50}] (* G. C. Greubel, Oct 17 2017 *)

PARI

a(n)=n^9+n^6+n^4+1 \\ Charles R Greathouse IV, Oct 16 2015

Formula

a(n) = 1 + n^4 + n^6 + n^9 = 1001010001 (base n).

G.f.: -x*(x^9 -8*x^8 -406*x^7 -14592*x^6 -88496*x^5 -156316*x^4 -87762*x^3 -14744*x^2 -553*x -4)/(x-1)^10. - Colin Barker, May 27 2012