A072200 a(n)-th factorial is the smallest factorial containing exactly n 6's, or 0 if no such number exists.

3, 15, 23, 26, 32, 41, 35, 45, 50, 72, 63, 83, 84, 98, 89, 94, 91, 121, 99, 142, 117, 160, 129, 0, 127, 131, 132, 154, 153, 163, 170, 179, 190, 178, 166, 189, 217, 209, 206, 174, 208, 199, 207, 211, 214, 245, 263, 175, 240, 255, 295, 234, 213, 296, 286, 266, 278

Offset

1,1

Comments

It is conjectured that a(24)=0 since no factorial < 10000 contained just 24 sixes.

Links

Table of n, a(n) for n=1..57.

Example

a(2)=15 since the 15th factorial, i.e., 15!=1307674368000, contains exactly two 6's.

Mathematica

Do[k = 1; While[ Count[IntegerDigits[k! ], 6] != n, k++ ]; Print[k], {n, 1, 60}]

Crossrefs

Cf. A072240, A072220, A072208, A072204, A072199, A072178, A072177, A072163 & A072124.

Sequence in context: A083793 A324127 A083934 * A106403 A225365 A225060

Adjacent sequences: A072197 A072198 A072199 * A072201 A072202 A072203

Keyword

base,nonn

Author

Shyam Sunder Gupta, Jul 30 2002

Extensions

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

Status

approved