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A196508
a(n) = 2^n*(n^2 - n + 4)-4.
1
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
0,2
REFERENCES
Jolley, Summation of Series, Dover (1961), eq. (46) on page 8.
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 ).
PROG
(Magma) [2^n*(n^2-n+4)-4: n in [0..30]]; // Vincenzo Librandi, Oct 05 2011
CROSSREFS
Sequence in context: A057333 A196432 A302815 * A121257 A145563 A125669
KEYWORD
nonn,easy
AUTHOR
R. J. Mathar, Oct 03 2011
STATUS
approved