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

1,1

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.

Links

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

Formula

a(n) = A260310(2n).

Example

see A260310.

Mathematica

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

Crossrefs

Cf. A260310, A260408, A260410.

Sequence in context: A257225 A092456 A232724 * A257509 A232570 A029522

Adjacent sequences: A260406 A260407 A260408 * A260410 A260411 A260412

Keyword

nonn

Author

Robert G. Wilson v, Jul 24 2015

Status

approved