A353221 Squarefree base-2 Fermat pseudoprimes divisible by a Wieferich prime.

3581761, 5173169, 5968873, 23872213, 36974341, 53711113, 107023281, 427294141, 490950461, 526359289, 546649741, 550230409, 753532781, 803264281, 836683849, 1115578101, 1168492417, 1193557093, 1540454761, 1632785701, 2129304997, 2295209281, 2677147201

Offset

1,1

Comments

Subsequence of A001567.

The least term that is divisible by both 1093 and 3511 is a(799) = 7015325908501 = 937 * 1093 * 1951 * 3511. - Amiram Eldar, May 05 2022

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

PrimeGrid, Subproject status.

Example

3581761 = 29 * 113 * 1093, so it is a base-2 pseudoprime divisible by the Wieferich prime 1093 and is squarefree.

Prog

(PARI) /* The following program is valid up to the current search bound for Wieferich primes, about 10^19 as of May 03 2022 (cf. PrimeGrid); the program may miss terms above that bound if there is another Wieferich prime */
forcomposite(c=1, , if(Mod(2, c)^(c-1)==1, if(Mod(c, 1093)==0 || Mod(c, 3511)==0, if(issquarefree(c), print1(c, ", ")))))

Crossrefs

Cf. A001220, A001567, A158358, A219346, A247830, A247831, A295740.

Sequence in context: A053078 A209911 A235077 * A352220 A214173 A183970

Adjacent sequences: A353218 A353219 A353220 * A353222 A353223 A353224

Keyword

nonn

Author

Felix Fröhlich, May 01 2022

Status

approved