A179335 - OEIS

%I #13 Jun 29 2022 13:40:36

%S 2,3,5,7,11,3,7,19,2,2,3,3,41,3,7,3,5,61,7,7,3,7,3,89,7,101,3,7,109,3,

%T 2,3,3,3,149,5,5,3,7,3,7,181,19,3,7,19,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,

%U 2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,401,409,19,2,3,3,3,3,449,5,61,3,7,7,7

%N a(n) is the smallest prime which appears as a substring of the decimal representation of prime(n).

%C a(n) < 10 iff prime(n) is in A179336;

%C a(n) = prime(n) iff prime(n) is in A033274. [Corrected by _M. F. Hasler_, Aug 27 2012]

%H Reinhard Zumkeller, <a href="/A179335/b179335.txt">Table of n, a(n) for n = 1..10000</a>

%o (PARI) A179335(n)={my(p=prime(n),m=0,M); for(d=1,n, M=10^d; n=p; until(n<=M || !n\=10, isprime(n%M) & (!m || m>n%M) & m=n%M); m & return(m))} \\ _M. F. Hasler_, Aug 27 2012

%o (Python)

%o from sympy import isprime, prime

%o def a(n):

%o     s = str(prime(n))

%o     ss = set(int(s[i:i+1+l]) for i in range(len(s)) for l in range(len(s)))

%o     return min(t for t in ss if isprime(t))

%o print([a(n) for n in range(1, 94)]) # _Michael S. Branicky_, Jun 29 2022

%Y Cf. A000040, A070024, A019546, A092629, A104250, A019546, A034844, A179336, A193238.

%K base,nonn

%O 1,1

%A _Reinhard Zumkeller_, Jul 11 2010