A196508 a(n) = 2^n*(n^2 - n + 4)-4.

0, 4, 20, 76, 252, 764, 2172, 5884, 15356, 38908, 96252, 233468, 557052, 1310716, 3047420, 7012348, 15990780, 36175868, 81264636, 181403644, 402653180, 889192444, 1954545660, 4278190076, 9328132092, 20266876924, 43889197052

Offset: 0

Author

R. J. Mathar, Oct 03 2011

Keywords

• nonn
• easy

References

• Jolley, Summation of Series, Dover (1961), eq. (46) on page 8.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..3000
• Index entries for linear recurrences with constant coefficients, signature (7,-18,20,-8)

Programs

Magma

[2^n*(n^2-n+4)-4: n in [0..30]]; // Vincenzo Librandi, Oct 05 2011

Formula

a(n) = 2*2 + 4*4 + 7*8 + 11*16 + 16*32 + ... (n terms of A000124*A000079).

a(n) = 4*A053545(n).

G.f.: 4*x*(1 - 2*x + 2*x^2) / ( (x-1)*(2*x-1)^3 ).