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A260409 Bisection of A260310. 3
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified January 19 19:49 EST 2019. Contains 319309 sequences. (Running on oeis4.)