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 A261232 #16 Mar 30 2017 21:53:25 %S A261232 1,2,4,9,21,50,124,320,850,2295,6251,17113,47014,129606,358839,998806, %T A261232 2796094,7869801,22251148,63141640,179701240,512744600,1466635090, %U A261232 4205423896,12087339724,34816804311,100469592522,290336059741,839932833291,2432050970421,7047731703138,20440131344751,59334695322384,172409162871824,501489513690424 %N A261232 a(n) = number of steps to reach 0 when starting from k = 3^n and repeatedly applying the map that replaces k with k - (sum of digits in base-3 representation of k). %F A261232 a(0) = 1; for n >= 1, a(n) = A261234(n-1) + a(n-1). %F A261232 a(n) = A261231(3^n). %F A261232 a(n) = 1 + A261233(n). %o A261232 (Scheme, two variants) %o A261232 (definec (A261232 n) (if (zero? n) 1 (+ (A261234 (- n 1)) (A261232 (- n 1))))) %o A261232 (define (A261232 n) (A261231 (A000244 n))) %Y A261232 One more than A261233. %Y A261232 Cf. A000244, A261231. %Y A261232 Cf. also A213710. %K A261232 nonn %O A261232 0,2 %A A261232 _Antti Karttunen_, Aug 13 2015 %E A261232 Terms from a(24) onward added from the output of _Hiroaki Yamanouchi_'s program by _Antti Karttunen_, Aug 16 2015