The On-Line Encyclopedia of Integer Sequences (OEIS)

A379768 revision #10

A379768

a(n) is the smallest prime p such that omega(p^n + 1) = n.

2, 3, 5, 43, 17, 47, 151, 1697, 59, 2153, 521, 13183, 30089, 66569, 761

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OFFSET

1,1

COMMENTS

2 * 10^6 < a(16) <= 206874667; a(18) = 33577;

LINKS

FORMULA

A219018(n) <= a(n) <= A280005(n).

EXAMPLE

a(3) = 5 is the smallest prime number of the set {p(i)} = {5, 11, 13, 19, 23, ...} where omega(p(i)^3 + 1) = 3.

PROG

(PARI) a(n) = forprime(p=2, oo, if(omega(p^n+1) == n, return(p)));

CROSSREFS

KEYWORD

nonn,more,hard

AUTHOR

Daniel Suteu, Jan 06 2025

STATUS

editing