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 A175435 #16 Oct 09 2013 17:01:42 %S A175435 0,1,0,1,4,0,4,2,0,7,5,6,1,3,6,11,10,9,17,5,6,1,8,6,13,11,0,16,14,3, %T A175435 19,31,6,31,11,9,16,14,3,10,17,6,22,2,9,16,32,21,10,44,15,13,29,0,35, %U A175435 34,51,10,58,39,13,29,27,16,5,51,28,17,15,4,38,18,7 %N A175435 (Digit sum of 3^n) mod n. %H A175435 Nathaniel Johnston, <a href="/A175435/b175435.txt">Table of n, a(n) for n = 1..5000</a> %e A175435 a(5) = 4 because digsum(3^5) mod 5 = digsum(243) mod 5 = 9 mod 5 = 4. %p A175435 read(transforms): A175435 := proc(n) return digsum(3^n) mod n: end proc: seq(A175435(n), n=1..50); # _Nathaniel Johnston_, Oct 09 2013 %o A175435 (PARI) a(n) = sumdigits(3^n) % n; \\ _Michel Marcus_, Oct 09 2013 %Y A175435 Cf. A000244, A004166, A067862; A000079, A001370, A175434, A175169. %K A175435 nonn,base %O A175435 1,5 %A A175435 _N. J. A. Sloane_, Dec 03 2010