A106107 Primes with minimal digit = 7.

7, 79, 97, 787, 797, 877, 887, 977, 997, 7789, 7877, 7879, 8779, 8887, 9787, 9887, 77797, 77899, 77977, 77999, 78779, 78787, 78797, 78877, 78887, 78889, 78977, 78979, 78989, 79777, 79889, 79979, 79987, 79997, 79999

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

Res:= NULL:
count:= 0:
for d from 1 while count < 100 do
  for m from 3^d to  2*3^d-1 while count < 100 do
  L:= convert(m, base, 3)[1..d];
  if min(L) <> 0 then next fi;
  x:= add((L[i]+7)*10^(i-1), i=1..d);
  if isprime(x) then count:= count+1; Res:= Res, x; fi
od od:
Res; # Robert Israel, Jan 07 2020

Mathematica

Select[Prime[Range[8000]], Min[IntegerDigits[ # ]]==7&]

Crossrefs

Sequence in context: A106110 A082992 A261181 * A020471 A065902 A140613

Adjacent sequences: A106104 A106105 A106106 * A106108 A106109 A106110

Keyword

nonn,base

Author

Zak Seidov, May 07 2005

Status

approved