A091931 Change the first bit to 0 in binary notation for the n-th prime.

0, 1, 1, 3, 3, 5, 1, 3, 7, 13, 15, 5, 9, 11, 15, 21, 27, 29, 3, 7, 9, 15, 19, 25, 33, 37, 39, 43, 45, 49, 63, 3, 9, 11, 21, 23, 29, 35, 39, 45, 51, 53, 63, 65, 69, 71, 83, 95, 99, 101, 105, 111, 113, 123, 1, 7, 13, 15, 21, 25, 27, 37, 51, 55, 57, 61, 75, 81, 91, 93, 97, 103

Offset: 1

Author

Reinhard Zumkeller, Feb 14 2004

Keywords

• nonn
• base
• easy

Comments

a(n) = A053645(A000040(n)).

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A091932.

Programs

Mathematica

FromDigits[Rest[IntegerDigits[#,2]],2]&/@Prime[Range[80]] (* Harvey P. Dale, Apr 20 2012 *)

PARI

for(n=1,72,p=prime(n);p-=2^(#binary(p)-1);print1(p,", ")) \\ Washington Bomfim, Jan 18 2011

Formula

a(n) = A000040(n) - 2^(A035100(n)-1).