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A340750
Primes p such that the number of primes that divide p-q for at least one prime q < p is prime.
1
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
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
Sequence in context: A157437 A213677 A330775 * A375096 A031134 A144231
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Jan 19 2021
STATUS
approved