The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A045510 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A045510

Factorials having initial digit '2'.
(history; published version)

#19 by Susanna Cuyler at Sun Jul 19 02:11:49 EDT 2020

STATUS

reviewed

approved

#18 by Michel Marcus at Sun Jul 19 02:05:51 EDT 2020

STATUS

proposed

reviewed

#17 by Amiram Eldar at Sun Jul 19 01:53:54 EDT 2020

STATUS

editing

proposed

#16 by Amiram Eldar at Sun Jul 19 01:41:46 EDT 2020

FORMULA

a(n) = A000142(A045521(n)). - Amiram Eldar, Jul 19 2020

CROSSREFS

Cf. A000142.

STATUS

approved

editing

#15 by Harvey P. Dale at Sat Mar 21 15:46:18 EDT 2020

STATUS

editing

approved

#14 by Harvey P. Dale at Sat Mar 21 15:46:15 EDT 2020

MATHEMATICA

Select[Range[50]!, IntegerDigits[#][[1]]==2&] (* Harvey P. Dale, Mar 21 2020 *)

STATUS

approved

editing

#13 by Bruno Berselli at Wed Dec 13 04:17:06 EST 2017

STATUS

proposed

approved

#12 by Michel Marcus at Wed Dec 13 03:31:03 EST 2017

STATUS

editing

proposed

#11 by Michel Marcus at Wed Dec 13 03:30:58 EST 2017

COMMENTS

Benford's law shows that this sequence will contain about (log 3 - log 2)/log 10 =~ 18% of factorials. [From __Charles R Greathouse IV_, Nov 13 2010]

PROG

(PARI) lista(nn) = {for (n=1, nn, if (digits(n!)[1] == 2, print1(n!, ", ")); ); } \\ Michel Marcus, Dec 13 2017

STATUS

approved

editing

#10 by N. J. A. Sloane at Tue Feb 07 15:57:54 EST 2017

STATUS

editing

approved