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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

Table of n, a(n) for n=2..106.

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: A197124 A032759 A142711 * A229875 A230199 A275542

Adjacent sequences:  A093335 A093336 A093337 * A093339 A093340 A093341

KEYWORD

base,nonn

AUTHOR

Cino Hilliard, Apr 25 2004

STATUS

approved

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Last modified July 24 02:31 EDT 2021. Contains 346270 sequences. (Running on oeis4.)