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A077721
Primes which can be expressed as sum of distinct powers of 7.
10
7, 2801, 17207, 19559, 120401, 134513, 134807, 137201, 840743, 842759, 842801, 941249, 943601, 958007, 958049, 958343, 960793, 5782001, 5784409, 5899307, 5899601, 5899657, 5901659, 6591089, 6607903, 6706393, 6708787, 6722801, 6722857, 6723193
OFFSET
1,1
COMMENTS
Primes whose base 7 representation contains only zeros and 1's.
LINKS
MAPLE
pos := 0:for i from 1 to 4000 do b := convert(i, base, 2); s := sum(b[j]*7^(j-1), j=1..nops(b)): if(isprime(s)) then pos := pos+1:a[pos] := s:fi: od:seq(a[j], j=1..pos);
MATHEMATICA
Select[Prime[Range[10^6]], Max[IntegerDigits[#, 7]]<=1 &] (* Vincenzo Librandi, Sep 07 2018 *)
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Nov 19 2002
EXTENSIONS
More terms from Sascha Kurz, Jan 03 2003
STATUS
approved