A139784 a(4n+1)=2a(4n), a(4n+2)=2a(4n+1), a(4n+3)=2a(4n+2), a(4n+4)=2a(4n+3)+A007583(n).

0, 0, 0, 0, 1, 2, 4, 8, 19, 38, 76, 152, 315, 630, 1260, 2520, 5083, 10166, 20332, 40664, 81499, 162998, 325996, 651992, 1304667, 2609334, 5218668, 10437336, 20877403, 41754806, 83509612, 167019224, 334049371, 668098742, 1336197484, 2672394968

Offset

0,6

Comments

a(0), a(4), a(8) and a(12) are the first terms of A111420. - R. J. Mathar, May 18 2008

Links

Table of n, a(n) for n=0..35.

Index entries for linear recurrences with constant coefficients, signature (2, 0, 0, 5, -10, 0, 0, -4, 8).

Formula

a(4n+s) = 2^s*(-1/45+7*16^n/90-4^n/18), s=0,1,2,3. - R. J. Mathar, May 18 2008

a(0)=0, a(1)=0, a(2)=0, a(3)=0, a(4)=1, a(5)=2, a(6)=4, a(7)=8, a(8)=19, a(n)=2*a(n-1)+5*a(n-4)-10*a(n-5)-4*a(n-8)+8*a(n-9). - Harvey P. Dale, Jan 21 2013

Mathematica

LinearRecurrence[{2, 0, 0, 5, -10, 0, 0, -4, 8}, {0, 0, 0, 0, 1, 2, 4, 8, 19}, 40] (* Harvey P. Dale, Jan 21 2013 *)

Crossrefs

Cf. a(0), a(4), a(8), a(12) in A111420.

Sequence in context: A293542 A049960 A018306 * A247235 A369683 A261663

Adjacent sequences: A139781 A139782 A139783 * A139785 A139786 A139787

Keyword

nonn

Author

Paul Curtz, May 16 2008

Extensions

Edited and extended by R. J. Mathar, May 18 2008

Status

approved