OFFSET
1,1
COMMENTS
In other words, these are numbers that are the product of two distinct primes whose prime indices differ by at most two.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
FORMULA
MAPLE
R:= NULL;
p:= 2; q:= 3;
for n from 1 to 100 by 2 do
r:= nextprime(q);
R:= R, p*q, p*r;
p:= q; q:= r;
od:
R; # Robert Israel, Apr 22 2020
MATHEMATICA
a[n_] := Prime[Ceiling[n/2]] * Prime[Ceiling[(n + 3)/2]]; Array[a, 50] (* Amiram Eldar, Apr 04 2020 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Bobby Jacobs, Apr 03 2020
STATUS
approved