A361696 Semiprimes of the form k^2 + 5.

6, 9, 14, 21, 69, 86, 201, 329, 446, 489, 581, 681, 734, 789, 905, 1094, 1769, 1941, 2606, 2921, 3254, 3369, 3849, 3974, 4101, 4629, 4766, 6729, 7061, 7401, 8105, 8654, 9609, 9806, 10409, 10821, 11669, 12326, 13929, 17429, 17961, 19049, 20741, 23109, 23721, 24341, 27561, 30281, 31334, 32405

Offset

1,1

Links

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

Formula

a(n) = A242333(n)^2 + 5.

Example

69 is a term because 8^2 + 5 = 69 = 3*23.

Prog

(PARI) isok(k) = issquare(k-5) && (bigomega(k)==2); \\ Michel Marcus, Mar 27 2023

Crossrefs

Cf. A144255, A242333, A360739, A360740, A360741.

Intersection of A117951 and A001358.

Sequence in context: A106350 A217851 A218697 * A316015 A316016 A316017

Adjacent sequences: A361693 A361694 A361695 * A361697 A361698 A361699

Keyword

nonn,easy

Author

Elmo R. Oliveira, Mar 20 2023

Status

approved