A335233 Numbers m such that m!*i + 1 is composite for i = 1..m.

50, 66, 67, 76, 81, 110, 117, 120, 122, 157, 178, 183, 217, 219, 226, 235, 240, 242, 244, 250, 254, 260, 266, 269, 274, 275, 287, 289, 309, 326, 346, 354, 363, 379, 380, 386, 400, 407, 410, 417, 419, 443, 449, 451, 470, 474, 489, 493, 509, 513, 518, 541, 543

Offset

1,1

Comments

If m is a term, then A321805(m) = 0.

Links

Chai Wah Wu, Table of n, a(n) for n = 1..240

Mathematica

Select[Range@ 200, (f = #!; NoneTrue[f*Range[#] + 1, PrimeQ]) &] (* Robert Price, Sep 14 2020 *)

Prog

(Python)
from sympy import isprime
A335233_list, f = [], 1
for k in range(1, 100):
    f *= k
    g = 1
    for i in range(1, k+1):
        g += f
        if isprime(g):
            break
    else:
        A335233_list.append(k)

Crossrefs

Cf. A321805.

Sequence in context: A007692 A025285 A092541 * A180103 A102803 A224559

Adjacent sequences: A335230 A335231 A335232 * A335234 A335235 A335236

Keyword

nonn

Author

Chai Wah Wu, Jun 09 2020

Status

approved