cp's OEIS Frontend

A123171 a(1) = 123, a(n) = sum of digits of all previous terms.

%I A123171 #10 Nov 16 2024 22:14:51
%S A123171 123,6,12,15,21,24,30,33,39,51,57,69,84,96,111,114,120,123,129,141,
%T A123171 147,159,174,186,201,204,210,213,219,231,237,249,264,276,291,303,309,
%U A123171 321,327,339,354,366,381,393,408,420,426,438,453,465,480,492,507,519,534
%N A123171 a(1) = 123, a(n) = sum of digits of all previous terms.
%C A123171 a(1) = 123 a(2) = 1 + 2 + 3 = 6 a(3) = (1 + 2 + 3) + 6 = 12 a(4) = (1 + 2 + 3) + 6 + (1 + 2) = 15 a(5) = (1 + 2 + 3) + 6 + (1 + 2) + (1 + 5) = 21 a(6) = (1 + 2 + 3) + 6 + (1 + 2) + (1 + 5) + (2 + 1) = 24 a(7) = (1 + 2 + 3) + 6 + (1 + 2) + (1 + 5) + (2 + 1) + (2 + 4) = 30 ...
%C A123171 Essentially the same as A016052. - _R. J. Mathar_, Jun 18 2008
%H A123171 James C. McMahon, <a href="/A123171/b123171.txt">Table of n, a(n) for n = 1..10000</a>
%H A123171 Sergio Silva, <a href="http://ginasiomental.no.sapo.pt/materialc/mteste/teste.htm">Teste Numerico</a>.
%F A123171 a(n) = a(n-1) + sum of digits of a(n-1), a(1) = 123
%t A123171 s={123};sum=0;Do[sum=sum+Total[IntegerDigits[s[[-1]]]];AppendTo[s,sum],{n,54}];s (* _James C. McMahon_, Nov 16 2024 *)
%o A123171 (PARI) s=0; a=123; print1(a,","); for(n=1,100,dig=eval(Vec(Str(a)));s=s+sum(i=1,length(dig),dig[i]);print1(s,",");a=s)
%Y A123171 Cf. A004207.
%K A123171 nonn,base
%O A123171 1,1
%A A123171 Herman Jamke (hermanjamke(AT)fastmail.fm), Oct 02 2006