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A219044
Numbers k such that 3^k + 26 is prime.
16
1, 3, 4, 5, 7, 9, 11, 16, 24, 28, 49, 53, 63, 88, 137, 184, 217, 299, 300, 732, 815, 999, 1243, 1320, 1397, 1668, 2109, 2681, 4973, 5513, 12100, 14284, 14592, 35812, 38559, 49687, 53167, 66907, 88765, 98251, 113548, 137988, 139432, 148008
OFFSET
1,2
COMMENTS
a(45) > 2*10^5. - Robert Price, Nov 29 2013
EXAMPLE
3^3 + 26 = 53 (prime), so 3 is in the sequence.
MATHEMATICA
Do[If[PrimeQ[3^n + 26], Print[n]], {n, 10000}]
PROG
(PARI) is(n)=isprime(3^n+26) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
Cf. Sequences of numbers k such that 3^k + m is prime:
(m = 2) A051783, (m = -2) A014224, (m = 4) A058958, (m = -4) A058959,
(m = 8) A217136, (m = -8) A217135, (m = 10) A217137, (m = -10) A217347,
(m = 14) A219035, (m = -14) A219038, (m = 16) A205647, (m = -16) A219039,
(m = 20) A219040, (m = -20) A219041, (m = 22) A219042, (m = -22) A219043,
(m = 26) A219044, (m = -26) A219045, (m = 28) A219046, (m = -28) A219047,
(m = 32) A219048, (m = -32) A219049, (m = 34) A219050, (m = -34) A219051. Note that if m is a multiple of 3, 3^k + m is also a multiple of 3 (for k greater than 0), and as such isn't prime.
Sequence in context: A193339 A049646 A033556 * A032507 A325462 A063950
KEYWORD
nonn,more
AUTHOR
Nicolas M. Perrault, Nov 10 2012
EXTENSIONS
a(31)-a(44) from Robert Price, Nov 29 2013
STATUS
approved