OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
P. De Geest, World!Of Palindromic Primes
EXAMPLE
2,3,5 are palindromes, and consecutive primes, but they are not consecutive palindromes.
2,3,4 are consecutive palindromes, but they are not all primes.
The first time there are three consecutive palindromes which are all primes is 1878781, 1879781, 1880881. - N. J. A. Sloane, Aug 12 2021
PROG
(PARI) nxt(n)=my(d=digits(n)); i=(#d+1)\2; while(i&&d[i]==9, d[i]=0; d[#d+1-i]=0; i--); if(i, d[i]++; d[#d+1-i]=d[i], d=vector(#d+1); d[1]=d[#d]=1); sum(i=1, #d, 10^(#d-i)*d[i]) \\ From David A. Corneth at A002113
list(lim)=my(v=List(), p=1, q=2, r=3); while(p<=lim\=1, if(isprime(r), if(isprime(q), if(isprime(p), listput(v, p)); p=q; q=r; r=nxt(r), q=nxt(p=r); r=nxt(q)), q=nxt(p=nxt(r)); r=nxt(q))); Vec(v) \\ Charles R Greathouse IV, Aug 11 2021
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, May 15 1998
EXTENSIONS
New name from Charles R Greathouse IV, Aug 11 2021
STATUS
approved