OFFSET
1,2
LINKS
Daniel Starodubtsev, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = (A002385(n+1) - 1)/2. - Rémy Sigrist, Jan 01 2019
EXAMPLE
5 is in the sequence, because 2 * 5 + 1 = 11 is a prime palindrome.
MATHEMATICA
Select[Range[16000], And[PrimeQ@ #, PalindromeQ@ #] &[2 # + 1] &] (* Michael De Vlieger, Jan 01 2019 *)
PROG
(PARI) isok(n) = my(p=2*n+1, d=digits(p)); isprime(p) && (Vecrev(d) == d); \\ Michel Marcus, Jan 01 2019
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Daniel Starodubtsev, Dec 31 2018
STATUS
approved