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A242827

Primes formed by the initial digits of the decimal expansion of 1/14, starting at the first nonzero digit in the expansion.

7, 71, 71428571, 7142857142857, 7142857142857142857142857142857

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OFFSET

1,1

COMMENTS

a(6) has 104 digits. - Michel Marcus, May 26 2014

a(7) has 571 digits. - Harvey P. Dale, Mar 16 2026

LINKS

Table of n, a(n) for n=1..5.

MATHEMATICA

Select[Table[FromDigits[PadRight[{}, n, {7, 1, 4, 2, 8, 5}]], {n, 2000}], PrimeQ] (* Harvey P. Dale, Mar 16 2026 *)

PROG

(PARI) lista(nn) = {v = [7, 1, 4, 2, 8, 5]; n = 0; for (i=0, nn, n = 10*n+ v[(i % 6)+1]; if (ispseudoprime(n), print1(n, ", ")); ); } \\ Michel Marcus, May 26 2014

CROSSREFS

Cf. A021018.

Corresponding sequences for 1/k: A242824 (k=7), A093676 (k=12), A242826 (k=13), A242828 (k=17), A242833 (k=19).

Sequence in context: A022503 A063861 A093632 * A077332 A222833 A388134

Adjacent sequences: A242824 A242825 A242826 * A242828 A242829 A242830

KEYWORD

nonn,base

AUTHOR

Felix Fröhlich, May 23 2014

STATUS

approved

URL: https://oeis.org/A242827

⇱ A242827 - OEIS