cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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).

Original entry on oeis.org

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

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Author

Paul Curtz, May 16 2008

Keywords

Comments

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

Crossrefs

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

Programs

  • 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 *)

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

Extensions

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