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

123, 6, 12, 15, 21, 24, 30, 33, 39, 51, 57, 69, 84, 96, 111, 114, 120, 123, 129, 141, 147, 159, 174, 186, 201, 204, 210, 213, 219, 231, 237, 249, 264, 276, 291, 303, 309, 321, 327, 339, 354, 366, 381, 393, 408, 420, 426, 438, 453, 465, 480, 492, 507, 519, 534

Offset

1,1

Comments

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 ...

Essentially the same as A016052. - R. J. Mathar, Jun 18 2008

Links

James C. McMahon, Table of n, a(n) for n = 1..10000

Sergio Silva, Teste Numerico.

Formula

a(n) = a(n-1) + sum of digits of a(n-1), a(1) = 123

Mathematica

s={123}; sum=0; Do[sum=sum+Total[IntegerDigits[s[[-1]]]]; AppendTo[s, sum], {n, 54}]; s (* James C. McMahon, Nov 16 2024 *)

Prog

(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)

Crossrefs

Cf. A004207.

Sequence in context: A015042 A062233 A351406 * A125097 A302211 A308004

Adjacent sequences: A123168 A123169 A123170 * A123172 A123173 A123174

Keyword

nonn,base

Author

Herman Jamke (hermanjamke(AT)fastmail.fm), Oct 02 2006

Status

approved