A164265 Partial sums of A162766.

4, 7, 19, 28, 64, 91, 199, 280, 604, 847, 1819, 2548, 5464, 7651, 16399, 22960, 49204, 68887, 147619, 206668, 442864, 620011, 1328599, 1860040, 3985804, 5580127, 11957419, 16740388, 35872264, 50221171, 107616799, 150663520, 322850404

Offset

1,1

Links

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

Index entries for linear recurrences with constant coefficients, signature (1,3,-3).

Formula

a(n) = 3*a(n-2)+7 for n > 2; a(1) = 4, a(2) = 7.

a(n) = (11-4*(-1)^n)*3^(1/4*(2*n-1+(-1)^n))/2-7/2.

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

Mathematica

LinearRecurrence[{1, 3, -3}, {4, 7, 19}, 40] (* Harvey P. Dale, Aug 28 2016 *)

Prog

(Magma) T:=[ n le 2 select 5-n else 3*Self(n-2): n in [1..33] ]; [ n eq 1 select T[1] else Self(n-1)+T[n]: n in [1..#T]];
(PARI) a(n)=if(n%2, 15, 7)*3^(n\2)\2-3 \\ Charles R Greathouse IV, Jul 15 2011

Crossrefs

Cf. A162766, A164123 (partial sums of A162436).

Sequence in context: A173017 A063605 A024824 * A174465 A006381 A318099

Adjacent sequences: A164262 A164263 A164264 * A164266 A164267 A164268

Keyword

nonn,easy

Author

Klaus Brockhaus, Aug 11 2009

Status

approved