A349732 Smallest k such that A349194(k) = n, or 0 if no such k exists.

1, 2, 3, 4, 5, 6, 7, 8, 9, 19, 0, 24, 0, 25, 32, 26, 0, 27, 0, 28, 34, 29, 0, 35, 50, 0, 36, 43, 0, 37, 0, 44, 38, 0, 52, 39, 0, 0, 0, 46, 0, 61, 0, 47, 54, 0, 0, 48, 70, 55, 0, 49, 0, 63, 56, 71, 0, 0, 0, 57, 0, 0, 72, 80, 58, 65, 0, 0, 0, 59, 0, 66, 0, 0, 0, 0, 74, 67, 0, 82, 90

Offset: 1

Author

Bernard Schott, Nov 28 2021

Keywords

• nonn
• base

Comments

Composite numbers m for which a(m) = 0 are in A349733.

Examples

			a(10) = 19 since 1*(1+9) = 10 and no integer du < 19 gives d*(d+u) = 10.
		

Crossrefs

Cf. A349194, A349733.

Formula

If p prime >= 11, a(p) = 0.