OFFSET
1,2
LINKS
Charles R Greathouse IV and Donovan Johnson, Table of n, a(n) for n = 1..70 (terms < 10^23; first 55 terms from Charles R Greathouse IV).
Mark Dominus, More sawed-off shotguns, 2007.
David Eppstein, Triangular numbers with many factors, 2007.
Shyam Sunder Gupta Fascinating Triangular Numbers.
EXAMPLE
a(4)=28: 28 is a triangular number and has 6 divisors. Number of divisors of all triangular numbers less than 28 is less than 6. So 28 is a highly composite triangular number.
PROG
(PARI) r=0; for(n=1, 1e7, t=if(n%2, numdiv(n)*numdiv((n+1)/2), numdiv(n/2)*numdiv(n+1)); if(t>r, r=t; print1(n*(n+1)/2", "))) \\ Charles R Greathouse IV, Feb 01 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Shyam Sunder Gupta, Oct 26 2002
STATUS
proposed