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 A358977 #9 Dec 12 2022 01:34:17 %S A358977 1,2,3,5,6,7,10,11,13,14,15,17,19,21,22,23,26,29,30,31,34,35,37,38,39, %T A358977 41,43,46,47,49,53,54,55,57,58,59,61,62,63,67,69,71,73,74,78,79,81,82, %U A358977 83,85,86,87,89,91,93,94,95,97,98,101,102,103,106,107,109,110 %N A358977 Numbers that are coprime to the sum of their primorial base digits (A276150). %C A358977 Numbers k such that gcd(k, A276150(k)) = 1. %C A358977 The primorial numbers (A002110) are terms. These are also the only primorial base Niven numbers (A333426) in this sequence. %C A358977 Includes all the prime numbers. %C A358977 The numbers of terms not exceeding 10^k, for k = 1, 2, ..., are 7, 59, 603, 6047, 60861, 608163, 6079048, 60789541, 607847981, 6080015681... . Conjecture: The asymptotic density of this sequence exists and equals 6/Pi^2 = 0.607927... (A059956), the same as the density of A094387. %H A358977 Amiram Eldar, <a href="/A358977/b358977.txt">Table of n, a(n) for n = 1..10000</a> %e A358977 3 is a term since A276150(3) = 2, and gcd(3, 2) = 1. %t A358977 With[{max = 4}, bases = Prime@Range[max, 1, -1]; nmax = Times @@ bases - 1; sumdig[n_] := Plus @@ IntegerDigits[n, MixedRadix[bases]]; Select[Range[nmax], CoprimeQ[#, sumdig[#]] &]] %o A358977 (PARI) is(n) = {my(p=2, s=0, m=n, r); while(m>0, r = m%p; s+=r; m\=p; p = nextprime(p+1)); gcd(n, s)==1; } %Y A358977 Cf. A059956, A276150, A333426. %Y A358977 Subsequences: A000040, A002110. %Y A358977 Similar sequences: A094387, A339076, A358975, A358976, A358978. %K A358977 nonn,base %O A358977 1,2 %A A358977 _Amiram Eldar_, Dec 07 2022