login
A109304
Numbers n such that string reversal of n is a substring of n-th prime.
3
7, 94, 281, 886, 16638, 60757, 642469, 689301, 784911, 3631421, 7144652, 7967301, 9428958, 17741923, 75060705, 141521639, 1060975242, 3087218304, 32644390236, 43670299761
OFFSET
1,1
COMMENTS
a(21) > pi(2*10^12). [From Donovan Johnson, May 08 2010]
EXAMPLE
94th prime, 491, contains 49 = the string reversal of its index;
281st prime, 1823, contains 182 = the string reversal of its index;
7144652nd prime, 125644177, contains 2564417 = the string reversal of its index; etc.
MATHEMATICA
fQ[n_] := StringPosition[ ToString[ Prime[n]], StringReverse[ ToString[n]]] != {}; Do[ If[ fQ[n], Print[n]], {n, 107350907, 2 10^9}] (* Robert G. Wilson v, Jun 28 2005 *)
CROSSREFS
Corresponding primes form A109305.
Sequence in context: A218835 A219417 A220405 * A134113 A071584 A132114
KEYWORD
base,nonn
AUTHOR
Zak Seidov, Jun 25 2005
EXTENSIONS
a(14)-a(16) from Robert G. Wilson v, Jun 28 2005
a(17)-a(20) from Donovan Johnson, May 08 2010
STATUS
approved