A260408 Bisection of A260310.

3, 7, 11, 7, 17, 29, 41, 53, 31, 71, 29, 107, 61, 41, 131, 53, 157, 113, 179, 239, 131, 79, 73, 127, 127, 229, 223, 113, 199, 73, 317, 181, 43, 269, 241, 89, 193, 101, 89, 211, 331, 167, 313, 409, 97, 113, 401, 480, 193, 109, 457, 241, 431

Offset: 1

Author

Robert G. Wilson v, Jul 24 2015

Keywords

• nonn

Comments

Lesser (member) of the n-th pair in A260310.

Most of the terms are prime, 97.25%, but there are composites, 2.75%: 480, 960, 990, 1200, 1170, 1950, 1890, 2610, ..., . They seem to all be congruent 0 (mod 6).

Conjecture: when a(n) is prime, A260409(n) is composite and vice versa. No contradictions in the first 10000 terms.

A260408 sorted without repeats: 3, 7, 11, 17, 29, 31, 41, 43, 53, 61, 71, 73, 79, 89, 97, 101, ..., .

Primes that have not appeared yet (10000 terms examined): 2, 5, 13, 19, 23, 37, 47, 59, 67, 83, 103, 139, 151, 163, 191, 197, ..., .

Examples

			See A260310.
		

Links

• Robert G. Wilson v, Table of n, a(n) for n = 1..9906

Crossrefs

Cf. A260310, A260409, A260410.

Programs

Mathematica

(* first run the Mmca in A260310 and then *) Take[ Transpose[ lst][[1]], 75]

Formula

a(n) = A260310(2n-1).