OFFSET
1,2
COMMENTS
Each prime p > 2 is palindrome in at least base 1 and base p-1, since p = 1*(p-1)^1 + 1*(p-1)^0 and p = 1*1^(p-1) + 1*1(p-2) + ... + 1*1^1 + 1*1^0.
LINKS
Attila Olah, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = A126071(prime(n)). - Charles R Greathouse IV, Jun 19 2014
EXAMPLE
a(621) = 9 because the 621st prime (4591) is a palindrome in 9 bases: base 1, 19, 20, 24, 33, 37, 51, 54 and 4590 (4591 = 1*4590^1 + 1*4590^0).
PROG
(PARI) ispal(v) = {for(i=1, #v\2, if (v[i] != v[#v-i+1], return(0)); ); return(1); };
a(n) = {p = prime(n); 1 + sum(i=2, p, ispal(digits(p, i))); } \\ Michel Marcus, Sep 04 2013
CROSSREFS
KEYWORD
easy,base,nonn
AUTHOR
Attila Olah (jolafix(AT)gmail.com), May 06 2008, corrected May 08 2008
STATUS
approved