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A186782 Primes of the form k*6^m-1 with k prime and m an integer. 2

%I #18 Sep 08 2022 08:45:56

%S 2,11,17,29,41,71,101,107,113,137,173,179,251,257,281,317,353,401,431,

%T 467,617,641,647,653,677,683,761,821,827,941,977,1181,1193,1361,1373,

%U 1433,1511,1613,1697,1877,1901,1907,2081,2153,2237,2273,2297,2333,2381,2411,2591

%N Primes of the form k*6^m-1 with k prime and m an integer.

%C Companion sequence to A185069.

%e 5*6^1-1 = 29 is prime and therefore a term.

%e 7*6^2-1 = 251 is prime and therefore a term.

%e 17*6^13-1 = 222031798271 is prime and therefore a term (see also its companion in A185069).

%t maxM = 4; p = Prime[Range[PrimePi[2*6^maxM]]];Sort[Flatten[Table[Select[p + 1, PrimeQ[#/6^k] &], {k, 0, maxM}] - 1]] (* _T. D. Noe_, Feb 28 2011 *)

%o (Magma) IsA186782:=function(n); k:=n+1; while k mod 6 eq 0 do k:=(k div 6); end while; return IsPrime(k); end function; [ n: n in PrimesUpTo(3000) | IsA186782(n) ]; // _Klaus Brockhaus_, Mar 01 2011

%Y Cf. A185069.

%K nonn

%O 1,1

%A _Gilbert Mozzo_, Feb 26 2011

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Last modified April 24 16:34 EDT 2024. Contains 371961 sequences. (Running on oeis4.)