A332952 Squarefree semiprimes which never occur in A245486.

46, 58, 74, 94, 106, 118, 122, 134, 142, 158, 166, 194, 202, 206, 214, 262, 267, 274, 278, 298, 309, 314, 326, 334, 339, 346, 358, 362

Offset

1,1

Comments

Also squarefree semiprimes which never occur in A332951.

This sequence is infinite. It appears that all terms can be divisible by 2 or 3.

If A014664(i) = A014664(j) for some 1 < i < j, then 2*prime(i) is a term. See A245486 for more information.

Links

Table of n, a(n) for n=1..28.

Romanian Master in Mathematics Contest, Bucharest, 2020, Problem 6

Example

a(2) = 58 because when 2^m - 1 or 2^m + 1 is divisible by 29, it's also divisible by 113. Therefore, there's no integer k such that A245486(k) = A006530(k) * A006530(k+1) = 58.

Crossrefs

Cf. A000040, A006530, A006881, A014664, A245486, A332951.

Sequence in context: A119385 A330243 A326646 * A308099 A308252 A322161

Adjacent sequences: A332949 A332950 A332951 * A332953 A332954 A332955

Keyword

nonn,more

Author

Jinyuan Wang, Mar 04 2020

Status

approved