A324333 Numbers d such that A324331(x) = d^2 only when x is a squarefree semiprime (A006881).

1, 2, 4, 6, 11, 12, 14, 16, 18, 20, 21, 22, 24, 25, 27, 29, 30, 32, 34, 35, 36, 38, 39, 41, 42, 43, 44, 45, 47, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 64, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 79, 81, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 97, 98, 100

Offset: 1

Author

Michel Marcus, Feb 23 2019

Keywords

• nonn

Comments

Problem posed by Albert A. Mullin, who asks if this sequence is infinite.

Links

• B. Alspach, Research problems, Problem 18, Discrete Math 40 (1982), page 126.

Crossrefs

Cf. A000010, A000203, A006881.

Cf. A324331, A324334 (complement).