OFFSET
1,1
COMMENTS
The maximum exponent for each prime in the factorization of each term is one. - Harvey P. Dale, Jul 21 2021
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
The 20th triangular number, T(20) = 20*21/2 = 210 = 2 * 3 * 5 * 7, so 210 is a term.
T(1333) = 889111 = 23 * 29 * 31 * 43, so 889111 is a term.
MAPLE
q:= n-> map(i-> i[2], ifactors(n)[2])=[1$4]:
select(q, [seq(n*(n+1)/2, n=0..300)])[]; # Alois P. Heinz, Apr 04 2020
MATHEMATICA
Select[Accumulate[Range[300]], PrimeNu[#]==PrimeOmega[#]==4&] (* Harvey P. Dale, Jul 21 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jon E. Schoenfield, Apr 04 2020
STATUS
approved