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 A373831 #9 Jun 19 2024 09:32:27 %S A373831 0,3,8,11,13,16,18,21,26,29,31,34,36,39,44,47,49,52,54,57,62,65,67,70, %T A373831 72,75,80,83,85,88,90,93,98,101,103,106,108,111,116,119,121,124,126, %U A373831 129,134,137,139,142,144,147,152,155,157,160,162,165,170,173,175,178,180,183,188,191,193,196,198,201,206,209,212 %N A373831 Numbers whose primorial base representation has alternating digit sum that is a multiple of 3. %H A373831 Antti Karttunen, <a href="/A373831/b373831.txt">Table of n, a(n) for n = 1..20020</a> %H A373831 <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a> %e A373831 A049345(3) = 11, and the alternating digit sum is A373605(3) = 1-1 = 0, and as zero is a multiple of 3, 3 is included in this sequence. %e A373831 A049345(193) = 6201, and the alternating digit sum is (1+2)-(0+6) = -3, thus 193 is included in this sequence. %o A373831 (PARI) isA373831 = A373830; %Y A373831 Cf. A049345, A373605, A373830 (characteristic function). %K A373831 nonn,base %O A373831 1,2 %A A373831 _Antti Karttunen_, Jun 19 2024