A339347 Primes p such that p < (gpf((p - 1)/gpf(p - 1)))^4, where gpf(k) is the greatest prime factor of k, A006530.

5, 7, 11, 13, 19, 31, 37, 43, 61, 67, 71, 73, 79, 101, 131, 151, 191, 197, 211, 239, 251, 281, 311, 331, 401, 419, 421, 431, 443, 461, 463, 491, 521, 547, 571, 599, 601, 617, 647, 659, 677, 683, 727, 743, 827, 859, 883, 911, 947, 953, 967, 1013, 1093, 1103

Offset

1,1

Comments

Inspired by A339466. See the references there.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

alias(pf = NumberTheory:-PrimeFactors): gpf := n -> max(pf(n)):
is_a := n -> isprime(n) and n < (gpf((n-1)/gpf(n-1)))^4:
select(is_a, [$5..1150]);

Prog

(PARI) gpf(n) = if (n==1, 1, vecmax(factor(n)[, 1])); \\ A006530
isok(p) = isprime(p) && (p < (gpf((p - 1)/gpf(p - 1)))^4); \\ Michel Marcus, Dec 14 2020

Crossrefs

Cf. A006530, A339466.

Sequence in context: A045438 A176579 A154275 * A167460 A045439 A093078

Adjacent sequences: A339344 A339345 A339346 * A339348 A339349 A339350

Keyword

nonn

Author

Peter Luschny, Dec 13 2020

Status

approved