OFFSET
1,5
EXAMPLE
a(1)=1 because prime(1)*2-prime(2)*1=4-3=1; a(2)=1 because prime(1)*3-prime(3)*2=6-5=1.
MAPLE
A006881 := proc(n)
option remember;
if n = 1 then
6;
else
for a from procname(n-1)+1 do
if numtheory[bigomega](a)=2 and issqrfree(a) then
return a;
end if;
end do:
end if;
end proc:
A169730 := proc(n)
local p, k, pm, pk;
p := numtheory[factorset](A006881(n)) ;
pm := op(1, p) ;
pk := op(2, p) ;
k := numtheory[pi](pk) ;
m := numtheory[pi](pm) ;
abs(pm*k-pk*m) ;
end proc:
seq(A169730(n), n=1..72) ; # R. J. Mathar, Jun 02 2016
CROSSREFS
KEYWORD
nonn,less
AUTHOR
Juri-Stepan Gerasimov, Apr 28 2010
EXTENSIONS
Corrected by R. J. Mathar, Jun 02 2016
STATUS
approved