A272524 Refactorable triangular numbers.

1, 36, 136, 276, 1176, 2016, 2556, 2628, 3240, 4560, 11628, 12720, 12880, 18336, 18528, 25200, 32640, 32896, 51360, 64620, 73920, 86320, 89676, 100128, 114960, 115440, 126756, 131328, 148240, 166176, 248160, 253116, 265356, 270480, 294528, 295296, 320400, 345696, 373680, 380628, 400960, 401856, 438516

Offset: 1

Author

Waldemar Puszkarz, May 01 2016

Keywords

• nonn

Comments

Intersection of A000217 and A033950.

Examples

			36 is a term as the number of divisors of 36 (see A000005) is 9 which divides 36.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000217 (triangular numbers), A033950 (refactorable numbers), A063440 (number of divisors of triangular numbers), A000005 (number of divisors), A036907 (refactorable squares).

Programs

Mathematica

Select[PolygonalNumber@Range@1000, Divisible[#, DivisorSigma[0,#]]&]

PARI

for (n=1, 1000, t=n*(n+1)/2; t%numdiv(t)==0 && print1(t ", " ))