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A260408 Bisection of A260310. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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, ..., .

LINKS

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

FORMULA

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

EXAMPLE

See A260310.

MATHEMATICA

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

CROSSREFS

Cf. A260310, A260409, A260410.

Sequence in context: A335980 A153788 A167486 * A261103 A262505 A083754

Adjacent sequences:  A260405 A260406 A260407 * A260409 A260410 A260411

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Jul 24 2015

STATUS

approved

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Last modified July 6 08:51 EDT 2020. Contains 335476 sequences. (Running on oeis4.)