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 A088639 Smallest prime beginning with at least n n's (in decimal notation). 3
 2, 11, 223, 3331, 44449, 555557, 66666629, 777777701, 888888883, 99999999907, 1010101010101010101039, 11111111111111111111111, 12121212121212121212121223, 1313131313131313131313131301, 141414141414141414141414141497, 15151515151515151515151515151501 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS M. F. Hasler, Table of n, a(n) for n=0..100 MAPLE a:= proc(n) local d, h, s; s:= parse(cat(0, n\$n)); for d from 0 do for h to 10^d-1 do if isprime(s+h) then return s+h fi od: s:= s*10; od end: seq(a(n), n=0..16); # Alois P. Heinz, Feb 11 2021 PROG (PARI) A088639(n)={ local(p=10^#Str(n), d=1); n*=(p^n-1)/(p-1); until( (d*=10)*(n+1)>p=nextprime(n*d), ); p} /* M. F. Hasler, Jan 13 2009 */ (Python) from sympy import isprime def a(n): if n == 0: return 2 nns, i, pow10 = int(str(n)*n), 1, 1 while True: i = 1 while i < pow10: t = nns * pow10 + i if isprime(t): return t i += 2 pow10 *= 10 print([a(n) for n in range(16)]) # Michael S. Branicky, Feb 11 2021 CROSSREFS Cf. A088640. See A068120 for another version. See also A065584 - A065592. Sequence in context: A283512 A214217 A042805 * A269710 A162385 A244012 Adjacent sequences: A088636 A088637 A088638 * A088640 A088641 A088642 KEYWORD base,easy,nonn AUTHOR Amarnath Murthy, Oct 27 2003 EXTENSIONS More terms from Ray Chandler, Nov 01 2003 More cross-references and initial term added by M. F. Hasler, Jan 13 2009 STATUS approved

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Last modified August 3 19:43 EDT 2024. Contains 374909 sequences. (Running on oeis4.)