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A185708 Characteristic function of positive numbers that are primes ending in 7. 6

%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

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Last modified December 18 12:06 EST 2018. Contains 318229 sequences. (Running on oeis4.)