A082458 Multiply by 1, add 1, multiply by 2, add 2, etc., starting with 0.

0, 0, 1, 2, 4, 12, 15, 60, 64, 320, 325, 1950, 1956, 13692, 13699, 109592, 109600, 986400, 986409, 9864090, 9864100, 108505100, 108505111, 1302061332, 1302061344, 16926797472, 16926797485, 236975164790, 236975164804, 3554627472060, 3554627472075, 56874039553200, 56874039553216

Offset: 0

Author

Vladeta Jovovic, Apr 25 2003

Keywords

• nonn

Comments

Bisections: A007526 and A038154.

Links

• Paolo Xausa, Table of n, a(n) for n = 0..800

Crossrefs

Cf. A019464 (same, but start with 1), A019465 (start with 2), A019466 (start with 3).

Cf. A019460 .. A019463 & A082448 (similar, but first add, then multiply).

Programs

Mathematica

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

PARI

a(n)=if(n<2,0,if(n%2,(n+1)/2*(floor(exp(1)*((n-1)/2)!)-1),floor(exp(1)*(n/2)!)-1))

PARI

A082458(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

Formula

For n>=2, a(2n)=floor(e*n!)-1, a(2*n+1)=(n+1)*(floor(e*n!)-1). - Benoit Cloitre, Apr 28 2003

Extensions

Edited by M. F. Hasler, Feb 25 2018