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

1,2

Comments

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

Links

Table of n, a(n) for n=1..70.

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

Crossrefs

Cf. A000010, A000203, A006881.

Cf. A324331, A324334 (complement).

Sequence in context: A057661 A237277 A097954 * A081988 A244748 A245017

Adjacent sequences: A324330 A324331 A324332 * A324334 A324335 A324336

Keyword

nonn

Author

Michel Marcus, Feb 23 2019

Status

approved