login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A106107 Primes with minimal digit = 7. 2
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 (list; graph; refs; listen; history; text; internal format)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 18 11:30 EDT 2021. Contains 343995 sequences. (Running on oeis4.)