OFFSET
1,1
COMMENTS
Rotkiewicz conjectured that there are infinitely many Carmichael numbers k such that k-2 or k+2 are primes.
The terms were calculated using Pinch's tables of Carmichael numbers (see link below).
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..282 (terms below 10^22, calculated using data from Claude Goutier)
Claude Goutier, Compressed text file carm10e22.gz containing all the Carmichael numbers up to 10^22.
R. G. E. Pinch, Tables relating to Carmichael numbers.
Andrzej Rotkiewicz, On pseudoprimes having special forms and a solution of K. Szymiczek's problem, Acta Mathematica Universitatis Ostraviensis, Vol. 13, No. 1 (2005), pp. 57-71.
EXAMPLE
656601 is in the sequence since it is a Carmichael number (A002997) and both 656599 and 656603 are primes.
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, May 26 2017
STATUS
approved