1,2

Table of n, a(n) for n=1..20.

1 is a term since 20^1 + 3 = 23 is a prime.

Do[ If[ PrimeQ[ 20^n + 3], Print[n]], {n, 0, 100000}]

(PARI) is(n)=isprime(20^n + 3)

Cf. A339922.

Sequence in context: A342715 A050079 A314313 * A066980 A055052 A314314

Adjacent sequences: A339918 A339919 A339920 * A339922 A339923 A339924

nonn,more

Paul Bourdelais, Dec 23 2020

a(19)-a(20) correspond to probable primes discovered by Paul Bourdelais, Jan 06 2021

approved