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A093338 Scan primes, write down initial digit if it is a prime. 0
2, 3, 5, 7, 2, 2, 3, 3, 5, 5, 7, 7, 7, 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, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,1
LINKS
PROG
(PARI) firstpr(n) = { forprime(x=2, n, fd = eval(mid(Str(x), 1, 1)); if(isprime(fd), print1(fd", ")) ) } \ Get a substring of length n from string str starting at position s in str. mid(str, s, n) = { v =""; tmp = Vec(str); ln=length(tmp); for(x=s, s+n-1, v=concat(v, tmp[x]); ); return(v) }
CROSSREFS
Cf. A077648.
Sequence in context: A032759 A142711 A357096 * A229875 A230199 A275542
KEYWORD
base,nonn
AUTHOR
Cino Hilliard, Apr 25 2004
STATUS
approved

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Last modified March 29 05:48 EDT 2024. Contains 371265 sequences. (Running on oeis4.)