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A389004

Smallest k such that the sum of digits of k^2 in base 10 is divisible by n.

1, 2, 3, 2, 8, 24, 4, 13, 3, 8, 43, 264, 7, 134, 1374, 13, 167, 24, 17, 313, 8937, 43, 836, 60663, 67, 2236, 63, 134, 6833, 545793, 83, 16667, 1989417, 167, 29614, 264, 314, 74833, 20736417, 313, 134164, 82395387, 707, 298327, 1374, 836, 947617, 706399164, 1667, 1643167

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..50.

Hugo Pfoertner, Known terms < 5*10^10.

MATHEMATICA

a[n_]:=Module[{k=1}, While[!Divisible[Total[IntegerDigits[k^2]], n], k++]; k]; Array[a, 38] (* James C. McMahon, Sep 22 2025 *)

PROG

(PARI) a(n) = my(k=1); while (sumdigits(k^2) % n, k++); k;

(Python)

from itertools import count