OFFSET
1,1
MATHEMATICA
nsmall = Table[Infinity, 20];
For[i = 0, i <= 10^6, i++, p = PolygonalNumber[i];
n0 = Count[IntegerDigits[p], 4];
If[nsmall[[n0]] > p, nsmall[[n0]] = p]];
ReplaceAll[nsmall, Infinity -> "?"] (* Robert Price, Mar 22 2020 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
a(12)-a(18) from Giovanni Resta, Oct 30 2019
STATUS
approved