OFFSET
1,2
COMMENTS
Composite numbers in the sequence have two forms of symmetry.
LINKS
David A. Corneth, Table of n, a(n) for n = 1..10000
David A. Corneth, n, a(n), symmetric factorization of a(n)
David A. Corneth, PARI program
EXAMPLE
5445 = 3*11*5*11*3, so it is a term.
PROG
(PARI) isok(n) = (Vecrev(m=digits(n))==m) && (isprime(core(n)) || issquare(n)); \\ Michel Marcus, Jan 15 2019
(PARI) \\ See Corneth link \\ David A. Corneth, Jan 22 2019
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Vladimir Shevelev, Dec 11 2015
EXTENSIONS
Missing term 8 inserted by Martin Schlegel, Jan 15 2019
STATUS
approved