This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A175801 #12 May 12 2019 02:23:00 %S A175801 0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,2,0,0, %T A175801 0,2,0,2,2,2,2,2,2,2,2,2,0,0,0,0,0,0,2,2,0,2,0,2,0,2,2,2,0,0,0,0,0,0, %U A175801 0,0,0,0,0,2,0,2,0,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,2,0,0 %N A175801 Number of real zeros of the polynomial whose coefficients are the decimal digits of prime(n). %C A175801 a(n) is the number of real zeros of the polynomial Sum_{k>=0} d(k) x^k %C A175801 where d(k) are the digits of the decimal expansion of prime(n) = Sum_{k>=0} 10^k*d(k). %e A175801 a(167) = 2 because prime(167) = 991 => P(167,x) = 1 + 9*x + 9*x^2 has 2 real-valued roots, -0.8726779962... and -0.1273220038... %p A175801 A175801 := proc(n) d := convert(ithprime(n),base,10) ; P := add( op(i,d)*x^(i-1),i=1..nops(d)) ; [fsolve(P,x,real)] ; nops(%) ; end proc: %p A175801 seq(A175801(n),n=1..45) ; # _R. J. Mathar_, Dec 06 2010 %Y A175801 Cf. A173667. %K A175801 nonn,base %O A175801 1,32 %A A175801 _Michel Lagneau_, Dec 04 2010