A260409 Bisection of A260310.

8, 16, 18, 27, 45, 50, 54, 60, 64, 84, 99, 132, 147, 153, 162, 207, 220, 225, 228, 240, 242, 243, 245, 255, 256, 264, 280, 297, 315, 325, 336, 338, 343, 348, 364, 369, 375, 423, 425, 435, 440, 455, 460, 468, 475, 477, 486, 487, 507, 539, 552

Offset: 1

Author

Robert G. Wilson v, Jul 24 2015

Keywords

• nonn

Comments

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

a(n) ~ 11.0*n.

It appears that most of the terms are composite (97.25% out of the first 10000 terms), but there are some primes: 487, 983, 1093, 1231, 1277, 2143, 2207, 2749, ..., .

a(n) < a(n+1) for all n > 0 is false, a(3276) = a(3277)= 35407 with A260409(3276) equal to 29820 & A260409(3276) equal to 34350 and a(4228) = a(4229) = 45841 with A260409(4228) equal to 40260 & A260409(4229) equal to 41496.

Least term a(n) such that a(n+1) is k away: 3276, 21, 2, 18, 6, 5, 7, 44, 1, 3, ..., . (A260410).

Conjecture: when a(n) is composite, A260408(n) is prime and vice versa. No contradictions in the first 10000 terms.

Examples

			see A260310.
		

Links

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

Crossrefs

Cf. A260310, A260408, A260410.

Programs

Mathematica

(* first run the Mmca in A260310 and then *) Take[ Transpose[ lst][[2]], 60]

Formula

a(n) = A260310(2n).