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 A085824 Numbers n such that the smallest prime containing exactly n 0's (A037053) requires only two nonzero digits. 4
 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 23, 24, 25, 26, 27, 28, 30, 34, 35, 36, 37, 38, 39, 41, 44, 45, 48, 51, 52, 54, 55, 56, 57, 59, 61, 64, 66, 68, 77, 80, 83, 85, 97, 99, 100, 102, 103, 104, 106, 109, 111, 112, 114, 119, 120, 122, 127, 128 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS In the first one thousand primes containing exactly n zeros, 140 use just two digits. 1008 is in the sequence. Although this sequence probably thins out like the primes, it is infinite. For indices n listed here (and no others), A037053(n) = a*10^(n+1)+b with a in {1,...,9} and b in {1, 3, 7, 9}. The sequence of numbers *not* in this sequence is 13, 22, 29, 31, 32, 33, 40, 42, 43, ... - M. F. Hasler, Feb 19 2016 LINKS Hans Havermann, Table of n, a(n) for n = 1..310 PROG (PARI) is_A085824(n)=forstep(m=n=10^(n+1), 9*n, n, nextprime(m)

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Last modified August 5 04:03 EDT 2021. Contains 346457 sequences. (Running on oeis4.)