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A268705 Smallest n-digit prime having at least n-1 digits equal to 7. 2
2, 17, 277, 1777, 47777, 727777, 7477777, 77767777, 577777777, 1777777777, 67777777777, 377777777777, 7177777777777, 17777777777777, 577777777777777, 2777777777777777, 77777767777777777, 377777777777777777, 2777777777777777777, 71777777777777777777 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Michel Lagneau, Michael De Vlieger and Robert G. Wilson v, Table of n, a(n) for n = 1..1125

MATHEMATICA

f[n_] := Block[{k = 0, p = {}, r = 7(10^n - 1)/9, s = Range@ 10 - 8}, While[k < n, AppendTo[p, Select[r + 10^k*s, PrimeQ]]; k++]; p = Min@ Flatten@ p]; f[1] = 2; f[2] = 17; Array[f, 20]

CROSSREFS

Cf. A037067, A241100, A268702 - A268706, A268707, A241206, A266146.

Sequence in context: A176585 A086534 A198287 * A078367 A090306 A304857

Adjacent sequences:  A268702 A268703 A268704 * A268706 A268707 A268708

KEYWORD

nonn,base

AUTHOR

Michel Lagneau, Michael De Vlieger and Robert G. Wilson v, Feb 11 2016

STATUS

approved

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Last modified January 27 12:01 EST 2020. Contains 331295 sequences. (Running on oeis4.)