OFFSET

1,2

COMMENTS

Let c = product of composite numbers in the range [n(n-1)/2 + 1, n(n+1)/2], let p = product of prime numbers in the same range; then a(n) = c - p. Empty products = 1 by convention.

EXAMPLE

n = 1: no primes or composites hence 1-1= a(1)=0; n=2: range = 2 and 3, a(2)= (Product of composite numbers among next n numbers) - (product of primes among next n numbers) = empty product of composite numbers - 6 = 1-6 = -5; a(3)= 4*6 -5 as the next 3 numbers are (4,5,6).

CROSSREFS

KEYWORD

sign,easy

AUTHOR

Amarnath Murthy, Jun 10 2004

EXTENSIONS

More terms from Joshua Zucker, May 03 2006

STATUS

approved