A072163 a(n)-th factorial is the smallest factorial containing exactly n 2's, or 0 if no such number exists.

2, 14, 13, 30, 40, 47, 31, 46, 54, 49, 65, 76, 62, 69, 107, 78, 86, 115, 95, 121, 109, 165, 110, 113, 149, 151, 146, 137, 162, 159, 170, 191, 195, 174, 190, 196, 164, 209, 202, 173, 198, 248, 201, 262, 231, 205, 263, 233, 246, 256, 270, 244, 287, 200, 271, 250

Offset

1,1

Links

Table of n, a(n) for n=1..56.

Example

a(2)=14 since 14th factorial, i.e., 14!=87178291200, contains exactly two 2's.

Mathematica

Do[k = 1; While[ Count[IntegerDigits[k! ], 2] != n, k++ ]; Print[k], {n, 1, 60}]

Crossrefs

Cf. A072293, A072220, A072208, A072204, A072200, A072199, A072178, A072177, A072124.

Sequence in context: A158787 A174706 A307269 * A084674 A009774 A276553

Adjacent sequences: A072160 A072161 A072162 * A072164 A072165 A072166

Keyword

base,nonn

Author

Shyam Sunder Gupta, Jul 30 2002

Extensions

Edited and extended by Robert G. Wilson v, Jul 31 2002

Status

approved