%I
%S 0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
%T 0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,
%U 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0
%N Characteristic function of positive numbers that are primes ending in 7.
%H Antti Karttunen, <a href="/A185708/b185708.txt">Table of n, a(n) for n = 1..65537</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%o (PARI) A185708(n) = ((7==(n%10))&&isprime(n)); \\ _Antti Karttunen_, Oct 09 2018
%Y Cf. A030432 (primes of form 10n+7).
%K base,nonn
%O 1
%A _N. J. A. Sloane_, Feb 10 2011
