|
|
A179335
|
|
a(n) is the smallest prime which appears as a substring of the decimal representation of prime(n).
|
|
4
|
|
|
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, 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, 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
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
a(n) < 10 iff prime(n) is in A179336;
|
|
LINKS
|
|
|
PROG
|
(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
(Python)
from sympy import isprime, prime
def a(n):
s = str(prime(n))
ss = set(int(s[i:i+1+l]) for i in range(len(s)) for l in range(len(s)))
return min(t for t in ss if isprime(t))
|
|
CROSSREFS
|
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|