OFFSET

0,4

LINKS

Michael De Vlieger, Table of n, a(n) for n = 0..10000

Scott R. Shannon, Image of n=0..1000000.

EXAMPLE

a(21) = 2 as a(20) = 11 which has a digit sum of 2, and there has been two previous terms with a digit sum of two: a(3) = 2 and a(20) = 11.

MATHEMATICA

nn = 94; c[_] = 0; a[0] = k = 0; c[0] = 1; Do[a[n] = c[k]; k = Total@ IntegerDigits[a[n]]; c[k]++, {n, nn}]; Array[a, nn] (* Michael De Vlieger, Oct 15 2022 *)

PROG

(Python)

from itertools import islice

from collections import Counter

def sd(n): return sum(map(int, str(n)))

def agen(): # generator of terms

an, s, inventory = 0, 0, Counter([0])

while True:

yield an; an = inventory[s]; s = sd(an); inventory[s] += 1

print(list(islice(agen(), 95))) # Michael S. Branicky, Oct 21 2022

CROSSREFS

KEYWORD

nonn,base

AUTHOR

Scott R. Shannon, Oct 15 2022

STATUS

approved