OFFSET
1,1
COMMENTS
Subsequence of A192133. - Reinhard Zumkeller, Jun 26 2011
For n > 1: A078898(a(n)) = 4. - Reinhard Zumkeller, Apr 06 2015
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
C. Cobeli and A. Zaharescu, A game with divisors and absolute differences of exponents, Journal of Difference Equations and Applications, Vol. 20, #11 (2014) pp. 1489-1501, DOI: 10.1080/10236198.2014.940337. Also available as arXiv:1411.1334 [math.NT], 2014.
EXAMPLE
a(5) = prime(5)*prime(7) = 11*17 = 187.
MATHEMATICA
Table[Prime[n] Prime[n + 2], {n, 1, 40}] (* Robert G. Wilson v, Jan 22 2004 *)
Last[#]First[#]&/@Partition[Prime[Range[50]], 3, 1] (* Harvey P. Dale, May 08 2013 *)
PROG
(MuPAD) ithprime(i)*ithprime(i+2) $ i = 1..40 // Zerinvary Lajos, Feb 26 2007
(Sage)
def prime_gaps(n):
primegaps = []
nprimes = primes_first_n(n+1)
for i in range(2, n+1):
primegaps.append(nprimes[i]*nprimes[i-2])
return primegaps
print(prime_gaps(60)) # Zerinvary Lajos, Jul 08 2008
(Haskell)
a090076 n = a090076_list !! (n-1)
a090076_list = zipWith (*) a000040_list $ drop 2 a000040_list
-- Reinhard Zumkeller, Dec 17 2014
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Felix Tubiana, Jan 21 2004
EXTENSIONS
Extended by Robert G. Wilson v, Jan 22 2004
STATUS
approved