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A266999 Smallest number m such that A266998(m) = n. 3
1, 10, 4, 12, 6, 3, 2, 11, 5, 18, 7, 13, 9, 19, 8, 17, 115, 3789 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The next term is too large to include.

LINKS

Michel Marcus, Table of n, a(n) for n = 0..17

FORMULA

A266998(a(n)) = n and A266998(m) != n for m < a(n).

MATHEMATICA

a266999={};

f[n_]:=Total[IntegerDigits[n]*(IntegerDigits[n]+1)/2];

g[n_]:=NestWhileList[f[#]&, n, #>1&];

h[n_]:=Length[g[n]]-1;

a266998=h/@Range[10^6];

Do[AppendTo[a266999, First[Position[a266998, m]]], {m, 0, Max[a266998]}];

a266999//Flatten

PROG

(PARI) strd(n) = {my(d = digits(n)); sum(k=1, #d, d[k]*(d[k]+1)/2); }

nbi(n) = {my(nb=0); while(n != 1, n = strd(n); nb++; ); nb; }

a(n) = {my(m = 1); while(nbi(m) != n, m++); m; } \\ Michel Marcus, Jan 12 2016

CROSSREFS

Cf. A266998.

Sequence in context: A309707 A100844 A076587 * A166204 A329649 A040094

Adjacent sequences:  A266996 A266997 A266998 * A267000 A267001 A267002

KEYWORD

base,more,nonn

AUTHOR

Ivan N. Ianakiev, Jan 10 2016

STATUS

approved

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Last modified December 8 14:38 EST 2019. Contains 329865 sequences. (Running on oeis4.)