A372074 a(1) = 1; thereafter a(n+1) is obtained by appending the digit-sum of a(n) to a(n).

1, 11, 112, 1124, 11248, 1124816, 112481623, 11248162328, 1124816232838, 112481623283849, 11248162328384962, 1124816232838496270, 112481623283849627077, 11248162328384962707791, 11248162328384962707791101, 11248162328384962707791101103, 11248162328384962707791101103107, 11248162328384962707791101103107115

Offset

1,2

Links

Paolo Xausa, Table of n, a(n) for n = 1..270

Maple

s:=1; j1:=[s];
f:=proc(n) local t1, t2;
t1:=digsum(n);
t2:=length(t1); n*10^t2 + t1; end;
for n from 1 to 24 do s:=f(s); j1:=[op(j1), s]; od:
j1;

Mathematica

NestList[With[{s = DigitSum[#]}, #*10^IntegerLength[s] + s] &, 1, 20] (* Paolo Xausa, Jun 16 2024 *)

Prog

(Python)
from itertools import islice
def A372074_gen(): # generator of terms
    yield (a:=1)
    while True: yield (a:=(s:=sum(map(int, str(a))))+a*10**len(str(s)))
A372074_list = list(islice(A372074_gen(), 20)) # Chai Wah Wu, Jun 16 2024

Crossrefs

Cf. A372075.

Inspired by A359143.

Sequence in context: A375101 A361350 A361501 * A132939 A059996 A132938

Adjacent sequences: A372071 A372072 A372073 * A372075 A372076 A372077

Keyword

nonn,base

Author

N. J. A. Sloane, Jun 16 2024

Status

approved