OFFSET
0,6
COMMENTS
Odd composite numbers with placeholders for primes between them.
FORMULA
a(n) = 2*n - A128059(n)
a(0) = -1, a(n) = GCD(2n-1, (2n-2)!), n > 0. - Wesley Ivan Hurt, Jan 05 2014
MAPLE
# End program 1 [Johannes W. Meijer, Oct 25 2012]
A128060 := proc(n) local n1: n1:=2*n-1: if type(n1, prime) then A128060(n) := 1 else A128060(n) := n1 fi: end: seq(A128060(n), n=0..62);
# End program 2 [Johannes W. Meijer, Oct 25 2012]
MATHEMATICA
Table[2n - Numerator[(2n - 1)^2/(2(2n)!)], {n, 0, 74}] (* Alonso del Arte, Jan 05 2014 *)
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Feb 13 2007
STATUS
approved