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 A303822 #13 May 03 2018 17:48:38 %S A303822 1,3,3,27,3,9,3,27,27,9,3,81,3,9,9,7625597484987,3,81,3,81,9,9,3,81, %T A303822 27,9,27,81,3,27,3,27,9,9,9,729,3,9,9,81,3,27,3,81,81,9,3, %U A303822 22876792454961,27,81,9,81,3,81,9,81,9,9,3,243,3,9,81,19683,9,27,3,81 %N A303822 Multiplicative with a(p^k) = 3^a(k). %C A303822 This sequence contains every power of 3; see A303823 for the corresponding least indices. %C A303822 This sequence is a variant of A303809. %H A303822 Rémy Sigrist, <a href="/A303822/b303822.txt">Table of n, a(n) for n = 1..10000</a> %F A303822 a(n) = n iff n = A014222(k) for some k > 0. %F A303822 a(A002110(k)) = 3^k for any k >= 0. %F A303822 a(n) = 3 iff n is prime. %o A303822 (PARI) a(n) = my (f=factor(n)); prod (i=1, #f~, 3^a(f[i, 2])) %Y A303822 Cf. A002110, A014222, A303809, A303823. %K A303822 nonn,easy,mult %O A303822 1,2 %A A303822 _Rémy Sigrist_, May 01 2018