OFFSET

1,2

COMMENTS

Zero together with the even nonprimes. - Omar E. Pol, Aug 04 2009

The nonprime numbers (A018252) begin: 1,4,6,8,9,10,12,14,15,... So the words "prime" and "nonprime" normally refer to the natural numbers or positive integers: 1,2,3,4,5,6,... (Zero is not a member of A018252. See also the definition of A141468). - Omar E. Pol, Aug 04 2009

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (2,-1).

FORMULA

a(n) = 2*A087156(n).

MATHEMATICA

Drop[Range[0, 132, 2], {2}] (* Harvey P. Dale, May 05 2012 *)

PROG

(PARI) a(n)=if(n>1, 2*n, 0) \\ Charles R Greathouse IV, Apr 17 2024

(Python)

def A163300(n): return n<<1 if n>1 else 0 # Chai Wah Wu, Jul 31 2024

CROSSREFS

KEYWORD

nonn,easy

AUTHOR

Juri-Stepan Gerasimov, Jul 26 2009

EXTENSIONS

New definition from Charles R Greathouse IV, Jun 23 2024

STATUS

approved