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 A112661 #17 Nov 25 2024 08:56:01 %S A112661 1,1,1,3,5,9,8,4,3,6,4,4,5,4,4,4,3,2,9,5,7,3,6,7,7,2,7,7,7,3,8,9,2,10, %T A112661 3,6,10,10,8,10,10,10,3,5,9,8,4,3,6,4,4,5,4,4,4,3,2,9,5,7,3,6,7,7,2,7, %U A112661 7,7,3,8,9,2,10,3,6,10,10,8,10,10,10,3,5,9,8,4,3,6,4,4,5,4,4,4 %N A112661 Sum of digits of sum of previous 3 terms. %C A112661 Sum of digits, not iterated (i.e., not digital sum, reducing to a single digit) as we twice get a term of 10 which we do not reduce to 1. This is to tribonacci (A000073) as A030132 is to Fibonacci (A000045). This sequence has a preamble of 3 terms (1, 1, 1), then enters a cycle of length 39 (ending with 10, 10, 10). %H A112661 <a href="/index/Rec#order_39">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1). %F A112661 a(n+2) = sum of digits of (a(n) + a(n-1) + a(n-2)). a(n+2) = A007953(a(n) + a(n-1) + a(n-2)). %t A112661 a[0] = a[1] = a[2] = 1; a[n_] := a[n] = Total@ IntegerDigits[a[n-1] + a[n-2] + a[n-3]]; a /@ Range[0, 93] (* _Giovanni Resta_, Jun 17 2016 *) %Y A112661 Cf. A000073, A004090, A007953, A010888, A030132. %K A112661 base,easy,nonn %O A112661 0,4 %A A112661 _Jonathan Vos Post_ and Andrew Carmichael Post (andrewpost(AT)gmail.com), Dec 29 2005 %E A112661 Data and name corrected by _Giovanni Resta_, Jun 17 2016