|
|
A306591
|
|
a(n) is the denominator of 1/2 - 1/(prime(n)+1), where prime(n) is the n-th prime.
|
|
1
|
|
|
6, 4, 3, 8, 12, 7, 9, 20, 24, 15, 32, 19, 21, 44, 48, 27, 60, 31, 68, 72, 37, 80, 84, 45, 49, 51, 104, 108, 55, 57, 128, 132, 69, 140, 75, 152, 79, 164, 168, 87, 180, 91, 192, 97, 99, 200, 212, 224, 228, 115, 117, 240, 121, 252, 129, 264, 135, 272, 139, 141, 284, 147, 308, 312, 157
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MATHEMATICA
|
1/2-1/(#+1)&/@Prime[Range[70]]//Denominator (* Harvey P. Dale, Feb 19 2023 *)
|
|
PROG
|
(PARI) a(n) = denominator(1/2 - 1/(prime(n)+1));
(Python)
from sympy import prime
from fractions import Fraction
def a(n): return (Fraction(1, 2) - Fraction(1, (prime(n)+1))).denominator
|
|
CROSSREFS
|
Cf. A145979 (denominator of 1/2 - 1/(n+1)).
|
|
KEYWORD
|
nonn,frac
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|