A019461 Add 1, multiply by 1, add 2, multiply by 2, etc.; start with 0.

0, 1, 1, 3, 6, 9, 27, 31, 124, 129, 645, 651, 3906, 3913, 27391, 27399, 219192, 219201, 1972809, 1972819, 19728190, 19728201, 217010211, 217010223, 2604122676, 2604122689, 33853594957, 33853594971, 473950329594, 473950329609, 7109254944135, 7109254944151, 113748079106416

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..899
• Nick Hobson, Python program for this sequence

Crossrefs

Cf. A019463 (same, but start with 1), A019460 (start with 2), A019462 (start with 3), A082448 (start with 4).

Cf. A082458, A019464 .. A019466 (similar, but first multiply, then add).

Programs

Maple

A019461 := proc(n) option remember; if n = 0 then 0 elif n mod 2 = 1 then (n+1)/2+A019461(n-1) else (n/2)*A019461(n-1); fi; end;

Mathematica

Module[{a = 0}, Join[{a}, Flatten[Array[{a += #, a *= #} &, 20]]]] (* Paolo Xausa, Oct 24 2024 *)

PARI

A019461(n,a=0)={for(i=2,n+1,if(bittest(i,0),a*=i\2,a+=i\2));a} \\ M. F. Hasler, Feb 25 2018

Extensions

Edited by M. F. Hasler, Feb 25 2018