A157966 Number of 3's in A157733(n).

0, 1, 1, 1, 3, 3, 5, 5, 7, 9, 9, 11, 13, 13, 15, 17, 19, 19, 21, 23, 23, 25, 27, 29, 31, 33, 33, 35, 35, 37, 41, 43, 45, 45, 49, 49, 51, 53, 55, 57, 59, 59, 63, 63, 65, 65, 69, 73, 75, 75, 77, 79, 79, 83, 85, 87, 89, 89, 91, 93, 93, 97, 101, 103, 103, 105, 109, 111, 115, 115, 117

Offset

0,5

Comments

Odd numbers missing in the sequence: 39, 47, 61, 67, 71, 81, 95, 99, 107, 113, 137, 141 etc.

The numbers above are essentially 2*A060461(n) - 1. - Mikhail Kurkov, Dec 18 2021

Links

Table of n, a(n) for n=0..70.

Formula

a(n) = floor((prime(n)-2)/3) for n != 2. - Kevin Ryde, Apr 25 2024

Prog

(PARI) a(n) = if(n==2, 1, (prime(n)-2)\3); \\ Kevin Ryde, Apr 25 2024

Crossrefs

Cf. A157733, A060461.

Sequence in context: A095878 A341143 A369337 * A212597 A268188 A231608

Adjacent sequences: A157963 A157964 A157965 * A157967 A157968 A157969

Keyword

nonn,easy

Author

Paul Curtz, Mar 10 2009

Extensions

Edited and extended by R. J. Mathar, Mar 15 2009

Status

approved