A335233 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

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)

(PARI) isok(m) = my(f=m!); for (i=1, m, if (ispseudoprime(1+f*i), return(0))); 1; \\ Michel Marcus, Jan 19 2026

CROSSREFS

Cf. A321805.

Sequence in context: A007692 A025285 A092541 * A180103 A102803 A380871

Adjacent sequences: A335230 A335231 A335232 * A335234 A335235 A335236

KEYWORD

nonn

AUTHOR

Chai Wah Wu, Jun 09 2020

STATUS

approved