A157966 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

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