A362254 Reciprocal of n modulo largest prime smaller than n.

1, 1, 2, 1, 3, 1, 4, 5, 2, 1, 6, 1, 7, 9, 10, 1, 9, 1, 10, 13, 5, 1, 12, 8, 6, 14, 4, 1, 15, 1, 16, 21, 8, 25, 26, 1, 19, 25, 28, 1, 21, 1, 22, 29, 11, 1, 24, 16, 12, 19, 8, 1, 27, 18, 40, 32, 9, 1, 30, 1, 31, 41, 46, 49, 51, 1, 34, 45, 17, 1, 36, 1, 37, 49

Offset: 3

Author

Alois P. Heinz, Apr 13 2023

Keywords

• nonn
• look

Links

• Alois P. Heinz, Table of n, a(n) for n = 3..10000

Crossrefs

Cf. A008864, A122585, A151799.

Programs

Maple

a:= n-> n&^(-1) mod prevprime(n):
seq(a(n), n=3..100);

Python

from sympy import prevprime
def A362254(n): return pow(n,-1,prevprime(n)) # Chai Wah Wu, Apr 13 2023

Formula

a(n) = 1 <=> n in { A008864 }.