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 A328620 #11 Mar 13 2024 01:50:34
%S A328620 0,0,1,0,1,0,2,1,1,0,1,0,2,1,1,0,1,0,2,1,1,0,1,0,2,1,1,0,1,0,3,2,2,1,
%T A328620 2,1,2,1,1,0,1,0,2,1,1,0,1,0,2,1,1,0,1,0,2,1,1,0,1,0,3,2,2,1,2,1,2,1,
%U A328620 1,0,1,0,2,1,1,0,1,0,2,1,1,0,1,0,2,1,1,0,1,0,3,2,2,1,2,1,2,1,1,0,1,0,2,1,1,0
%N A328620 Number of nonleading zeros in primorial base expansion of n, a(0) = 0 by convention.
%H A328620 Antti Karttunen, <a href="/A328620/b328620.txt">Table of n, a(n) for n = 0..32768</a>
%H A328620 <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>.
%F A328620 a(n) = A001221(A328612(n)).
%F A328620 a(n) = A079067(A276086(n)).
%F A328620 a(A002110(n)) = n for all n >= 0.
%t A328620 a[n_] := Module[{k = n, p = 2, s = 0, r}, While[{k, r} = QuotientRemainder[k, p]; k != 0 || r != 0, If[r == 0, s++]; p = NextPrime[p]]; s]; Array[a, 100, 0] (* _Amiram Eldar_, Mar 13 2024 *)
%o A328620 (PARI) A328620(n) = { my(s=0, p=2); while(n, s += (0==(n%p)); n = n\p; p = nextprime(1+p)); (s); };
%Y A328620 Cf. A001221, A002110, A049345, A079067, A276086, A328612, A328614, A328615, A328616.
%Y A328620 Cf. A257510 for an analogous sequence.
%K A328620 nonn,base
%O A328620 0,7
%A A328620 _Antti Karttunen_, Oct 23 2019