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A304373 Numbers n with additive persistence = 4. 4
19999999999999999999999, 28999999999999999999999, 29899999999999999999999, 29989999999999999999999, 29998999999999999999999, 29999899999999999999999, 29999989999999999999999, 29999998999999999999999, 29999999899999999999999, 29999999989999999999999 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..10.

Eric Weisstein's World of Mathematics, Additive Persistence

FORMULA

A031286(a(n)) = 4.

EXAMPLE

Repeatedly taking the sum of digits starting with 19999999999999999999999 gives 199, 19, 10 and 1. There are four steps, so the additive persistence is 4 and 19999999999999999999999 is a member.

MATHEMATICA

Take[ Sort@ Flatten[ (FromDigits /@ Permutations@#) & /@ IntegerPartitions[ 199, {23}, Range@ 9]], 10000] (* first 10000 terms, Giovanni Resta, May 29 2018 *)

PROG

(PARI) nb(n) = {my(nba = 0); while (n > 9, n = sumdigits(n); nba++); nba; }

isok(n) = nb(n) == 4; \\ Michel Marcus, May 29 2018

CROSSREFS

Cf. A031286.

Cf. Numbers with additive persistence k: A304366 (k=1), A304367 (k=2), A304368 (k=3).

Sequence in context: A246254 A238360 A082566 * A316155 A216854 A008916

Adjacent sequences:  A304370 A304371 A304372 * A304374 A304375 A304376

KEYWORD

nonn,base

AUTHOR

Jaroslav Krizek, May 28 2018

STATUS

approved

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Last modified October 23 17:31 EDT 2019. Contains 328373 sequences. (Running on oeis4.)