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A112661 Sum of digits of sum of previous 3 terms. 2

%I #11 Jan 15 2023 17:59:50

%S 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 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 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 Sum of digits of sum of previous 3 terms.

%C 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).

%F 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 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 Cf. A000073, A004090, A007953, A010888, A030132.

%K base,easy,nonn

%O 0,4

%A _Jonathan Vos Post_ and Andrew Carmichael Post (andrewpost(AT)gmail.com), Dec 29 2005

%E Data and name corrected by _Giovanni Resta_, Jun 17 2016

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)