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.
%I A232093 #14 Sep 23 2024 04:00:46
%S A232093 1,7,30,87,202,403,726,1214,1911,2874,4158,5832,7968,10640,13933,
%T A232093 17937,22747,28464,35195,43054,52162,62644,74630,88257,103671,121020,
%U A232093 140462,162155,186267,212973,242453,274894,310483,349420,391909,438161,488388,542814,601667,665181,733594,807154,886109,970720,1061252,1157972,1261156,1371084,1488047,1612341
%N A232093 Position of 7^n among 7-smooth numbers (A002473).
%C A232093 Note that all powers of 7 are terms in A002473.
%C A232093 Polynomial of fourth order is sufficient for very accurate approximation of a(n).
%H A232093 Zak Seidov, <a href="/A232093/b232093.txt">Table of n, a(n) for n = 0..200</a>
%F A232093 a(n) ~ c * n^4, where c = log(7)^3/(24*log(2)*log(3)*log(5)) = 0.250503020417439... - _Vaclav Kotesovec_ and _Amiram Eldar_, Sep 22 2024
%e A232093 A002473(a(1)) = A002473(7) = 7.
%e A232093 A002473(a(2)) = A002473(30) = 49 = 7^2.
%e A232093 A002473(a(200)) = A002473(411921660) = 7^200.
%t A232093 ss7 = {}; Do[m = 7^n; s = Sum[1 + Floor[Log[2, 7^(n - k)/5^i/3^j]], {k, 0, n}, {i, 0, Log[5, 7^(n - k)]}, {j, 0, Log[3, 7^(n - k)/5^i]}]; AppendTo[ss7, {n, s}], {n, 0, 50}]; ss7
%Y A232093 Cf. A000420, A002473.
%K A232093 nonn
%O A232093 0,2
%A A232093 _Zak Seidov_, Nov 18 2013