A267320 - OEIS

A267320

Smallest m such that A267238(m) = n.

0, 1, 11, 2, 12, 112, 3, 13, 113, 23, 4, 14, 33, 24, 124, 5, 15, 115, 25, 125, 44, 6, 16, 116, 26, 45, 145, 36, 7, 17, 55, 27, 127, 255, 37, 137, 8, 18, 47, 28, 128, 247, 38, 57, 157, 9, 19, 119, 29, 67, 167, 39, 139, 457, 239, 49, 77, 68, 168, 277, 59, 159, 377, 259, 78, 178, 69, 169, 1169

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..68.

MATHEMATICA

seq={0}; f[n_]:=Total[IntegerDigits[n]*(IntegerDigits[n]+1)/2]; lst=f/@Range[10^5];

Do[AppendTo[seq, First[Position[lst, m]]], {m, 1, 100}]; seq//Flatten

PROG

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

a(n) = {m = 0; while(strd(m) != n, m++); m; } \\ Michel Marcus, Jan 13 2016

CROSSREFS