OFFSET
1,1
EXAMPLE
a(5)=15319 because 100000-15319 = 84681 = 291^2.
MATHEMATICA
Select[Prime[Range[160000]], IntegerQ[Sqrt[10^IntegerLength[#]-#]]&] (* Harvey P. Dale, May 24 2011 *)
PROG
(PARI) { PTS(m)=local(ct, sr, ptc); ct=0; sr=0; forprime(p=2, m, ptc=10^length(Str(p))-p; if(issquare(ptc), ct+=1; print1(p", "); sr+=1.0/p; )); print(); print("Found "ct" primes < "m); print("Sum of reciprocals = "sr); }
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jason Earls, May 30 2003
STATUS
approved