A059569 - OEIS

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A059569

Numbers k such that (7*3^k - 5)/2 is prime.

2, 4, 6, 8, 38, 66, 72, 126, 140, 152, 174, 332, 710, 820, 2528, 2582, 2668, 2776, 2982, 3826, 6144, 15778, 23518, 75504

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

a(23) > 20306. - Jinyuan Wang, Jan 29 2020

LINKS

Table of n, a(n) for n=1..24.

MATHEMATICA

Do[ If[ PrimeQ[ (7*3^n - 5)/2 ], Print[n] ], {n, 0, 4500} ]

PROG

(PARI) is(n)=ispseudoprime((7*3^n-5)/2) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A059528 ((7*3^k+5)/2 is prime).

Sequence in context: A329887 A108425 A215216 * A083433 A083435 A163502

Adjacent sequences: A059566 A059567 A059568 * A059570 A059571 A059572

KEYWORD

nonn,more

AUTHOR

Robert G. Wilson v, Feb 16 2001

EXTENSIONS

a(21)-a(22) from Jinyuan Wang, Jan 29 2020

a(23) from Michael S. Branicky, May 02 2023

a(24) from Michael S. Branicky, Oct 24 2024

STATUS

approved