A358352 a(n) is the smallest number k such that A358351(k) = n.

1, 3, 26, 38, 380, 1116, 12912, 95131, 342038, 3320210, 494204209, 773089018

Offset: 0

Author

Bernard Schott, Nov 19 2022

Keywords

• nonn
• base
• more

Examples

			19+sod(19)+pod(19) = 24+sod(24)+pod(24) = 31+sod(31)+pod(31) = 38, and there is no integer < 38 for which function A161351 has 3 preimages, so a(3) = 38.
		

Links

• Rémy Sigrist, C program

Crossrefs

Cf. A006064, A007953, A007954, A161351, A358350, A358351.

Programs

C

See Links section.

Mathematica

f[n_] := n + Total[(d = IntegerDigits[n])] + Times @@ d; s = With[{m = 10^7}, BinCounts[Table[f[n], {n, 1, m}], {1, m, 1}]]; FirstPosition[s, #] & /@ Range[0, Max[s]] // Flatten (* Amiram Eldar, Nov 19 2022 *)

PARI

first(n) = my(res = vector(n)); for(i = 1, n, c = i + sumdigits(i) + vecprod(digits(i)); if(c <= n, res[c]++ ) ); res; \\ A358351
lista(nn) = my(v=first(nn)); for (n=0, 20, my(vs = select(x->(x==n), v, 1)); if (#vs, print1(vs[1], ", "), break);); \\ Michel Marcus, Nov 20 2022

Extensions

a(4)-a(5) from Michel Marcus, Nov 19 2022

a(6)-a(9) from Amiram Eldar, Nov 19 2022

a(10)-a(11) from Rémy Sigrist, Nov 20 2022