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A152418 A sevens sequence: a(n)=(7^n - 1)/(2^(4 - 3*Mod[n, 2])). 1
0, 3, 3, 171, 150, 8403, 7353, 411771, 360300, 20176803, 17654703, 988663371, 865080450, 48444505203, 42388942053, 2373780754971, 2077058160600, 116315256993603, 101775849869403, 5699447592686571, 4987016643600750 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Colin Barker, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (0,50,0,-49).

FORMULA

a(n) = (7^n - 1)/(2^(4 - 3*Mod[n, 2])).

a(n) = 50*a(n-2)-49*a(n-4). - Colin Barker, Nov 06 2014

G.f.: 3*x*(7*x^2+x+1) / ((x-1)*(x+1)*(7*x-1)*(7*x+1)). - Colin Barker, Nov 06 2014

MATHEMATICA

a[n_] := (7^n - 1)/(2^(4 - 3*Mod[n, 2]));

Table[a[n], {n, 0, 30}]

PROG

PARI) concat(0, Vec(3*x*(7*x^2+x+1)/((x-1)*(x+1)*(7*x-1)*(7*x+1)) + O(x^100))) \\ Colin Barker, Nov 06 2014

CROSSREFS

Cf. A003462.

Sequence in context: A006845 A071536 A094755 * A273925 A113457 A113466

Adjacent sequences:  A152415 A152416 A152417 * A152419 A152420 A152421

KEYWORD

nonn,easy

AUTHOR

Roger L. Bagula, Dec 03 2008

STATUS

approved

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Last modified October 21 20:44 EDT 2019. Contains 328315 sequences. (Running on oeis4.)