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A352616 Numbers k such that A155085(k) is in A037074. 0
7, 17, 50, 71, 449, 851, 881, 1467, 2591, 5123, 9521, 18167, 29817, 34859, 38027, 39761, 52415, 84359, 90611, 92711, 106721, 147267, 179999, 204479, 206081, 342791, 388961, 596231, 606609, 847601, 922607, 1060307, 1256879, 1292831, 1389671, 1590983, 1976015, 2157227, 2169971, 2268449, 2571911 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers k such that k + A000203(k) is the product of a twin prime pair.

LINKS

Table of n, a(n) for n=1..41.

EXAMPLE

a(3) = 50 is a term because 50 + A000203(50) = 143 = 11*13 where (11,13) is a twin prime pair.

MAPLE

filter:= proc(n) local t, s; t:= n + numtheory:-sigma(n);

  if t::even or not issqr(t+1) then return false fi;

  s:= sqrt(t+1);

  isprime(s+1) and isprime(s-1)

end proc:

select(filter, [$1..3000000]);

CROSSREFS

Cf. A000203, A037074, A155085.

Sequence in context: A045821 A262754 A115914 * A094534 A262106 A081632

Adjacent sequences:  A352613 A352614 A352615 * A352617 A352618 A352619

KEYWORD

nonn

AUTHOR

J. M. Bergot and Robert Israel, Mar 23 2022

STATUS

approved

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Last modified October 3 10:58 EDT 2022. Contains 357231 sequences. (Running on oeis4.)