A340750 Primes p such that the number of primes that divide p-q for at least one prime q < p is prime.

5, 7, 11, 29, 43, 53, 89, 109, 113, 127, 131, 173, 179, 181, 199, 263, 311, 379, 419, 433, 443, 449, 461, 467, 479, 523, 571, 577, 593, 601, 613, 631, 653, 709, 719, 733, 739, 757, 811, 823, 829, 853, 929, 937, 967, 971, 1019, 1031, 1049, 1153, 1181, 1321, 1381, 1399, 1409, 1439, 1451, 1453, 1459

Offset

1,1

Comments

Primes p such that A340743(A000720(p)) is prime.

Links

Robert Israel, Table of n, a(n) for n = 1..3000

Example

a(3) = 11 is a term because there are 2 primes that divide at least one of 11-2 = 9, 11-3 = 8, 11-5 = 6 and 11-7 = 4, namely 2 and 3, and 2 is prime.

Maple

filter:= proc(n) local L, P, i, t;
  L:= [seq(ithprime(n)-ithprime(i), i=1..n-1)];
  P:= `union`(seq(numtheory:-factorset(t), t=L));
  isprime(nops(P))
end proc:
map(ithprime, select(filter, [$1..1000]));

Crossrefs

Cf. A000720, A340743.

Sequence in context: A157437 A213677 A330775 * A031134 A144231 A050299

Adjacent sequences: A340747 A340748 A340749 * A340751 A340752 A340753

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Jan 19 2021

Status

approved