A369613 - OEIS

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A369613

Numbers k such that ceiling(10^k/7) is prime.

1

1, 4, 10, 16, 130, 1900, 5356, 181960

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OFFSET

1,2

COMMENTS

a(n) == 4 (mod 6) for n > 1.

1 and numbers k such that (10^k + 3)/7 is prime.

LINKS

Table of n, a(n) for n=1..8.

EXAMPLE

4 is a term because ceiling(10^4/7) = 1429 is prime.

.

n | k = a(n) | ceiling(10^k/7)

--+----------+-----------------

1 | 1 | 2

2 | 4 | 1429

3 | 10 | 1428571429

4 | 16 | 1428571428571429

CROSSREFS

Sequence in context: A061682 A246882 A038240 * A211160 A310535 A310536

Adjacent sequences: A369610 A369611 A369612 * A369614 A369615 A369616

KEYWORD

nonn,more,hard,changed

AUTHOR

Jon E. Schoenfield, Jan 27 2024

EXTENSIONS

a(8) from Jinyuan Wang, Nov 30 2024

STATUS

approved