cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A282021 Factorials with initial digit '7'.

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%I A282021 #19 Jul 19 2020 02:34:44
%S A282021 720,
%T A282021 710998587804863451854045647463724949736497978881168458687447040000000000000,
%U A282021 71569457046263802294811533723186532165584657342365752577109445058227039255480148842668944867280814080000000000000000000
%N A282021 Factorials with initial digit '7'.
%C A282021 Benford's law shows that this sequence will contain about (log(8) - log(7))/log(10) =~ 5.8% of all factorials.
%H A282021 Vincenzo Librandi, <a href="/A282021/b282021.txt">Table of n, a(n) for n = 1..22</a>
%H A282021 <a href="/index/Be#Benford">Index entries for sequences related to Benford's law</a>
%F A282021 a(n) = A000142(A045526(n)). - _Amiram Eldar_, Jul 19 2020
%t A282021 Select[Range[100]!, First[IntegerDigits[#]] == 7 &] (* _Vincenzo Librandi_, Feb 08 2017 *)
%Y A282021 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.
%K A282021 nonn,base
%O A282021 1,1
%A A282021 _N. J. A. Sloane_, Feb 07 2017