A068398 Number of digits in (2^n)*(n!).

1, 1, 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 13, 14, 16, 17, 19, 20, 22, 23, 25, 27, 28, 30, 32, 33, 35, 37, 38, 40, 42, 44, 46, 47, 49, 51, 53, 55, 57, 59, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 103, 105, 107, 109, 111, 113, 115, 117, 120

Offset: 0

Author

Benoit Cloitre, Mar 01 2002

Keywords

• nonn
• base

Crossrefs

Cf. A000165, A055642.

Programs

Mathematica

Table[IntegerLength[2^n n!],{n,0,70}] (* Harvey P. Dale, May 03 2024 *)

PARI

a(n) = log(n!*2^n)\log(10) + 1; \\ Michel Marcus, Oct 23 2020

Formula

a(n) = floor(log(n!*2^n)/log(10)) + 1.

a(n) = A055642(A000165(n)). - Michel Marcus, Oct 23 2020

Extensions

a(0)=1 prepended by Alois P. Heinz, Oct 23 2020