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 A366906 #7 Oct 28 2023 03:48:35 %S A366906 1,1,1,1,1,1,1,8,1,1,1,1,1,1,1,8,1,1,1,1,1,1,1,8,1,1,27,1,1,1,1,32,1, %T A366906 1,1,1,1,1,1,8,1,1,1,1,1,1,1,8,1,1,1,1,1,27,1,8,1,1,1,1,1,1,1,64,1,1, %U A366906 1,1,1,1,1,8,1,1,1,1,1,1,1,8,27,1,1,1,1,1 %N A366906 The largest exponentially evil divisor of n. %C A366906 The largest divisor of n that is an exponentially evil number (A262675). %C A366906 The number of exponentially evil divisors of n is A366902(n) and their sum is A366904(n). %H A366906 Amiram Eldar, <a href="/A366906/b366906.txt">Table of n, a(n) for n = 1..10000</a> %F A366906 Multiplicative with a(p^e) = p^max{k=1..e, k evil}. %F A366906 a(n) <= n, with equality if and only if n is exponentially evil number (A262675). %F A366906 a(n) >= 1, with equality if and only if n is a cubefree number (A004709). %t A366906 maxEvil[e_] := Module[{k = e}, While[OddQ[DigitCount[k, 2, 1]], k--]; k]; f[p_, e_] := p^maxEvil[e]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] %o A366906 (PARI) s(n) = {my(k = n); while(hammingweight(k)%2, k--); k;} %o A366906 a(n) = {my(f = factor(n)); prod(i = 1, #f~, f[i, 1]^s(f[i, 2]));} %Y A366906 Cf. A004709, A262675, A366902, A366904. %Y A366906 Similar sequences: A353897, A365683, A366905. %K A366906 nonn,easy,mult %O A366906 1,8 %A A366906 _Amiram Eldar_, Oct 27 2023