OFFSET
1,1
LINKS
A.H.M. Smeets, Table of n, a(n) for n = 1..20000
FORMULA
a(n) = A175228(n+1). - A.H.M. Smeets, Aug 19 2019
EXAMPLE
a(1) = 4 is the first composite number.
MAPLE
b:=proc(n) if isprime(n)=true then else n fi end: B:=[seq(b(n), n=2..250)]: seq(B[2*m-1], m=1..75); # Emeric Deutsch, Dec 09 2004
MATHEMATICA
Partition[Select[Range[200], CompositeQ], 2][[All, 1]] (* Jean-François Alcover, Mar 22 2023 *)
PROG
(Python)
from sympy import composite
def A099861(n): return composite((n<<1)-1) # Chai Wah Wu, Nov 14 2024
CROSSREFS
KEYWORD
nonn,easy,changed
AUTHOR
N. J. A. Sloane, Nov 19 2004
EXTENSIONS
More terms from Emeric Deutsch, Dec 09 2004
STATUS
approved