Numbers k that divide sigma(k*(k+1)/2).

Terms

a(0) =1a(1) =2a(2) =3a(3) =7a(4) =12a(5) =15a(6) =31a(7) =56a(8) =63a(9) =127a(10) =135a(11) =168a(12) =234a(13) =240a(14) =255a(15) =260a(16) =384a(17) =504a(18) =511a(19) =720a(20) =819a(21) =896a(22) =992a(23) =1023a(24) =1080a(25) =1344a(26) =1512a(27) =1638a(28) =2047a(29) =2240