cp's OEIS Frontend

A373839 Numbers k such that k and A276150(k) are both multiples of 3, where A276150 is the digit sum in the primorial base.

%I A373839 #9 Jun 20 2024 08:38:02
%S A373839 0,9,18,27,33,42,51,66,75,84,90,99,108,117,123,132,141,156,165,174,
%T A373839 180,189,198,207,213,222,231,246,255,264,270,279,288,297,303,312,321,
%U A373839 336,345,354,360,369,378,387,393,402,411,426,435,444,450,459,468,477,483,492,501,516,525,534,540,549,558,567,573,582
%N A373839 Numbers k such that k and A276150(k) are both multiples of 3, where A276150 is the digit sum in the primorial base.
%C A373839 If x and y are terms and if A329041(x,y) = 1 (i.e., when adding x and y together will not generate any carries in the primorial base), then x+y is also a term. This follows from the quasi-exponential nature of A276086 and because A373837 is a multiplicative semigroup. See also A373599.
%H A373839 Antti Karttunen, <a href="/A373839/b373839.txt">Table of n, a(n) for n = 1..12000</a>
%H A373839 <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>
%o A373839 (PARI) isA373839 = A373838;
%Y A373839 Intersection of A008585 and A373841.
%Y A373839 Indices of multiples of 3 in A373833.
%Y A373839 Cf. A276150, A329041, A373838 (characteristic function).
%Y A373839 Cf. also A373599, A373837.
%K A373839 nonn,base
%O A373839 1,2
%A A373839 _Antti Karttunen_, Jun 19 2024