OFFSET
1,1
LINKS
Antonio Roldán, Table of a(n) for a(n) <= 10^4
EXAMPLE
40 has a unique triangular proper divisor greater than 1: 10.
PROG
(PARI)
istriang(x)=issquare(8*x+1)
numpropdivtriang(n)={my(m=0); for(i=3, n/2, if(istriang(i)&&n/i==n\i, m+=1)); return(m)}
{t=0; for(n=1, 200, k=numpropdivtriang(n); if(k==1, t+=1; write("B203468.txt", t, " ", n)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Antonio Roldán, Jan 14 2013
STATUS
approved