A045517 Factorials with initial digit '5'.

5040, 51090942171709440000, 523022617466601111760007224100074291200000000, 5502622159812088949850305428800254892961651752960000000000

Offset: 1

Author

Jeff Burch

Keywords

• nonn
• base

Comments

Benford's law shows that this sequence will contain about (log 6 - log 5)/log 10 =~ 8% of factorials. [Charles R Greathouse IV, Nov 13 2010]

Links

• Index entries for sequences related to Benford's law

Crossrefs

For factorials with initial digit d (1 <= d <= 9) see A045509, A045510, A045511, A045516, A045517, A045518, A282021, A045519; A045520, A045521, A045522, A045523, A045524, A045525, A045526, A045527, A045528, A045529. See also A000142.

Programs

Mathematica

Select[Range[100]!,First[IntegerDigits[#]]==5&] (* Harvey P. Dale, Sep 06 2016 *)

Formula

a(n) = A000142(A045524(n)). - Amiram Eldar, Jul 19 2020