A139479 -id:A139479 - cp's OEIS frontend

A139484 Indices of Mersenne primes among primes of the form 24k + 7 (A107006).

1, 2, 5, 129, 1536, 5430, 13138099

Offset: 2

Artur Jasinski, Apr 23 2008

All Mersenne primes with the exception of the first one (3) are of the form 24*k + 7.

Sequence lists indices m where A139483(m) is a Mersenne prime.

			5 is in this sequence, because A107006(5) is a Mersenne prime.

Cf. A107006, A124477, A139479, A139483.

w = {2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607}; Do[w[[n]] = 2^w[[n]] - 1, {n, 1, Length[w]}]; c = 0; a = {}; Do[k = 24 n + 7; If[PrimeQ[k], c = c + 1; If[MemberQ[w, k], AppendTo[a, c]]], {n, 1, 10000000}]; a
With[{mps=2^#-1&/@MersennePrimeExponent[Range[20]]},Position[ Select[ 24*Range[0,10^8]+7,PrimeQ],?(MemberQ[mps,#]&)]]//Flatten (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale, Aug 20 2019 *)

Edited name and added example by Dmitry Kamenetsky, Jan 02 2011

a(8) from Charles R Greathouse IV, Mar 22 2011

A139480 a(n) = A000043(n) - 3.

Original entry on oeis.org

0, 2, 4, 10, 14, 16, 28, 58, 86, 104, 124, 518, 604, 1276, 2200, 2278, 3214, 4250, 4420, 9686, 9938, 11210, 19934, 21698, 23206, 44494, 86240, 110500, 132046, 216088, 756836, 859430, 1257784, 1398266, 2976218, 3021374, 6972590, 13466914, 20996008, 24036580, 25964948

Offset: 2

Artur Jasinski, Apr 22 2008

nonn

2^a(n)-1 is divisible by 3. For (2^a(n)-1)/3 see A124477.

For a(n)/2 see A139481.

Amiram Eldar, Table of n, a(n) for n = 2..48

Cf. A000043, A000668, A124477, A139479, A139481.

MersennePrimeExponent[Range[2, 48]] - 3 (* Amiram Eldar, Oct 17 2024 *)

Definition corrected by Omar E. Pol, May 23 2008
Edited by N. J. A. Sloane, May 23 2008
a(40)-a(42) from Amiram Eldar, Oct 17 2024

A139481 a(n) = A139480(n)/2.

Original entry on oeis.org

0, 1, 2, 5, 7, 8, 14, 29, 43, 52, 62, 259, 302, 638, 1100, 1139, 1607, 2125, 2210, 4843, 4969, 5605, 9967, 10849, 11603, 22247, 43120, 55250, 66023, 108044, 378418, 429715, 628892, 699133, 1488109, 1510687, 3486295, 6733457, 10498004, 12018290

Offset: 2

Artur Jasinski, Apr 22 2008

Amiram Eldar, Table of n, a(n) for n = 2..48

Cf. A000043, A000668, A124477, A139479, A139480, A146768.

(MersennePrimeExponent[Range[2, 48]] - 3)/2 (* Amiram Eldar, Oct 17 2024 *)

a(n) = A146768(n-1)-1. - R. J. Mathar, Mar 30 2011

Edited by N. J. A. Sloane, May 23 2008

A121290 a(n) = (2^prime(n) - 8)/24 for n>=2.

Original entry on oeis.org

0, 1, 5, 85, 341, 5461, 21845, 349525, 22369621, 89478485, 5726623061, 91625968981, 366503875925, 5864062014805, 375299968947541, 24019198012642645, 96076792050570581, 6148914691236517205

Offset: 1

Lekraj Beedassy, Aug 24 2006

Previous name was: (2^(p-3) - 1)/3, where p is an odd prime, i.e., p = A065091.

Cf. A000043, A000668, A124477, A139479, A139480.

Table[(2^Prime[n] - 8)/24, {n, 2, 100}] (* Artur Jasinski *)

New name from Joerg Arndt, Jul 21 2017

A139483 Numbers n such that 24n+7 is prime.

Original entry on oeis.org

0, 1, 3, 4, 5, 6, 8, 9, 11, 15, 18, 19, 20, 25, 26, 30, 31, 34, 38, 40, 41, 43, 44, 45, 51, 53, 54, 55, 58, 59, 60, 61, 64, 65, 69, 73, 74, 76, 78, 81, 83, 89, 93, 95, 96, 99, 104, 106, 110, 111, 113, 115, 116, 120, 128, 136, 138, 139, 141, 144, 146, 148, 149, 150, 151

Offset: 1

Artur Jasinski, Apr 23 2008

Cf. A107006, A124477, A139479.

a = {}; Do[If[PrimeQ[24 n + 7], AppendTo[a, n]], {n, 0, 200}]; a
Select[Range[0,200],PrimeQ[24#+7]&] (* Harvey P. Dale, Sep 02 2015 *)

is(n)=isprime(24*n+7) \\ Charles R Greathouse IV, Jun 06 2017

cp's OEIS Frontend

A139484 Indices of Mersenne primes among primes of the form 24k + 7 (A107006).

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A139480 a(n) = A000043(n) - 3.

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A139481 a(n) = A139480(n)/2.

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A121290 a(n) = (2^prime(n) - 8)/24 for n>=2.

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A139483 Numbers n such that 24n+7 is prime.

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