A390577 Remainder when (prime(n) * prime(n+1)) is divided by n.

0, 1, 2, 1, 3, 5, 1, 5, 1, 9, 3, 5, 8, 5, 1, 7, 12, 1, 7, 3, 13, 1, 4, 17, 22, 3, 5, 15, 21, 11, 21, 27, 2, 5, 29, 19, 24, 13, 31, 7, 9, 5, 12, 5, 8, 37, 6, 29, 43, 7, 46, 35, 18, 31, 51, 19, 53, 15, 16, 23, 20, 51, 32, 63, 31, 53, 59, 47, 8, 67, 63, 65, 16, 27, 32, 27

Offset

1,3

Links

Karl-Heinz Hofmann, Table of n, a(n) for n = 1..10000

Formula

a(n) = (prime(n) * prime(n+1)) mod n.

Example

a(3) = (prime(3) * prime(3+1)) mod 3 = (5 * 7) mod 3 = 35 mod 3 = 2.

Mathematica

a[n_]:=Mod[Prime[n]*Prime[n+1], n]; Array[a, 76] (* James C. McMahon, Nov 11 2025 *)

Prog

(Python)
from sympy import sieve
def A390577(n): return (sieve[n] * sieve[n+1]) % n

Crossrefs

Cf. A006094, A173956.

Sequence in context: A297519 A297749 A173588 * A286942 A125076 A220562

Adjacent sequences: A390574 A390575 A390576 * A390578 A390579 A390580

Keyword

nonn,easy

Author

Karl-Heinz Hofmann, Nov 11 2025

Status

approved