A262104 Pseudoprimes to base 7, written in base 7.

6, 34, 643, 1431, 2023, 2245, 3136, 5215, 6061, 6601, 10121, 12361, 16123, 20032, 25345, 33155, 41545, 42601, 42652, 44122, 45406, 50026, 54561, 56035, 66522, 66666, 105403, 110254, 112612, 113345, 113356, 123616, 135206, 140011, 151142, 151354, 153022, 153101, 153352, 155554

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = A007093(A005938(n)).

Mathematica

base = 7; t = {}; n = 1;
While[Length[t] < 40, n++;
If[! PrimeQ[n] && PowerMod[base, n - 1, n] == 1,
  AppendTo[t, FromDigits@IntegerDigits[n, 7]]]]; t
FromDigits[IntegerDigits[#, 7]]&/@Select[Range[40000], CompositeQ[#] && PowerMod[ 7, #-1, #]==1&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Feb 24 2018 *)

Prog

(PARI) lista(nn, b=7) = {for (n=1, nn, if (Mod(b, n)^(n-1)==1 && !ispseudoprime(n) && n>1, print1(subst(Pol(digits(n, b), x), x, 10), ", "); ); ); } \\ Michel Marcus, Sep 30 2015

Crossrefs

Cf. A005938 (pseudoprimes to base 7), A007093 (numbers in base 7).

Cf. A258189, A262101, A262102, A262103, A262105, A262154.

Sequence in context: A062819 A230246 A092336 * A161323 A003423 A230936

Adjacent sequences: A262101 A262102 A262103 * A262105 A262106 A262107

Keyword

nonn,base

Author

Abdul Gaffar Khan, Sep 11 2015

Status

approved