OFFSET
1,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
FORMULA
prime(n+1)-prime(n)=1 or p1*...*pk where p1, ..., pk are two or more distinct primes.
EXAMPLE
prime(69)-prime(68)=347-337=10=2*5.
MAPLE
L:=[]: for z to 1 do for k from 1 to 200 do p:=ithprime(k); q:=nextprime(p); x:=q-p; if not(isprime(x)) and issqrfree(x) then L:=[op(L), k] fi od od; L;
MATHEMATICA
Flatten[Position[Flatten[Differences/@Partition[Prime[Range[200]], 2, 1]], _?(!PrimeQ[#] && SquareFreeQ[#]&)]]//Rest (* Harvey P. Dale, Sep 10 2022 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Walter Kehowski, Jan 08 2006
STATUS
approved