A109763 Primes repeated.

2, 2, 3, 3, 5, 5, 7, 7, 11, 11, 13, 13, 17, 17, 19, 19, 23, 23, 29, 29, 31, 31, 37, 37, 41, 41, 43, 43, 47, 47, 53, 53, 59, 59, 61, 61, 67, 67, 71, 71, 73, 73, 79, 79, 83, 83, 89, 89, 97, 97, 101, 101, 103, 103, 107, 107, 109, 109, 113, 113, 127, 127, 131, 131

Offset: 1

Author

Giovanni Teofilatto, Aug 13 2005

Keywords

• easy
• nonn

Programs

Mathematica

With[{prs=Prime[Range[40]]},Riffle[prs,prs]] (* Harvey P. Dale, Oct 10 2014 *)

Formula

a(n) = A000040(ceiling(n/2)). - Jon Perry, Oct 29 2014