A101756 Number of divisors of highly composite triangular numbers.

1, 2, 4, 6, 9, 16, 18, 20, 24, 36, 40, 48, 90, 112, 128, 144, 162, 168, 192, 240, 320, 480, 576, 648, 768, 1024, 1280, 1344, 1512, 1536, 1728, 1920, 2304, 2880, 3072, 3200, 3456, 3888, 4480, 5760, 6144, 6912, 7680, 8640, 9216, 13824, 16128, 23040, 25088

Offset: 1

Author

Ray Chandler, Dec 22 2004

Keywords

• nonn

Links

• Charles R Greathouse IV and Donovan Johnson, Table of n, a(n) for n = 1..70 (first 55 terms from _Charles R Greathouse IV_).

Crossrefs

Cf. A076711, A101755.

Programs

PARI

t1=1;r=0;for(n=1,2e9,t2=n+1;t2=numdiv(t2/if(n%2,2,1));if(t1*t2>r,r=t1*t2;print1(r", "));t1=t2) \\ Charles R Greathouse IV, Feb 01 2013

Formula

a(n) = A000005(A076711(n)) = A000005(A000217(A101755(n))).