A201914 Least prime p such that p+1 is divisible by 2^n and not by 2^(n+1).
2, 5, 3, 7, 47, 31, 191, 127, 1279, 3583, 5119, 6143, 20479, 8191, 81919, 294911, 1114111, 131071, 786431, 524287, 17825791, 14680063, 138412031, 109051903, 654311423, 1912602623, 738197503, 2818572287, 7247757311, 3758096383, 228707008511, 2147483647
Offset: 0
Keywords
References
- Laurențiu Panaitopol, Alexandru Gica, Arithmetic problems and number theory, Ed. Gil, Zalău, (2006), ch. 13, p. 78, pr. 5 (in Romanian).
Links
- Donovan Johnson, Table of n, a(n) for n = 0..1000
Crossrefs
Programs
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Magma
a:=[]; for n in [0..31] do k:=1; while not IsPrime(k*2^n-1) do k:=k+2; end while; Append(~a,k*2^n-1); end for; a; // Marius A. Burtea, Mar 10 2020
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Mathematica
Table[k = 1; While[p = k*2^n - 1; ! PrimeQ[p], k = k + 2]; p, {n, 0, 40}]
Comments