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A339307 Numbers n such that A228553(n) is prime. 2
11, 20, 24, 27, 32, 35, 37, 38, 68, 74, 78, 79, 82, 96, 98, 101, 103, 122, 137, 149, 161, 188, 209, 218, 239, 249, 258, 276, 293, 321, 325, 333, 363, 365, 372, 433, 445, 449, 499, 535, 567, 568, 580, 588, 594, 595, 622, 644, 656, 663, 666, 682, 688, 693, 721, 742, 754, 756, 760, 796, 814, 845 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..5000

EXAMPLE

a(3) = 24 is in the sequence because A228553(24) = 1987 is prime.

MAPLE

f:= proc(n)

  local S;

  S:= select(t -> isprime(t) and isprime(2*n-t), [seq(i, i=3..n, 2)]);

  add(t*(2*n-t), t=S)

end proc:

f(2):= 4:

select(isprime@f, [$1..1000]);

CROSSREFS

Cf. A228553, A339309.

Sequence in context: A230541 A053715 A250203 * A038581 A044054 A044435

Adjacent sequences:  A339304 A339305 A339306 * A339308 A339309 A339310

KEYWORD

nonn

AUTHOR

J. M. Bergot and Robert Israel, Nov 29 2020

STATUS

approved

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Last modified January 17 23:09 EST 2021. Contains 340249 sequences. (Running on oeis4.)