OFFSET

1,1

COMMENTS

The sequence is unbounded as a(n+1) is less than or equal to the n-th triangular number.

EXAMPLE

45 is a term because 21 + 45 = 66, 45 + 91 = 136, and 66 and 136 are triangular numbers.

PROG

(PARI) p=6; k=3; print1(p", "); for(n=1, 30, k=k+1; u=p+k*(k+1)/2; t=floor(sqrt(2*u)); while(u!=t*(t+1)/2, k=k+1; u=p+k*(k+1)/2; t=floor(sqrt(2*u))); p=k*(k+1)/2; print1(p", "))

CROSSREFS

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Jul 31 2002

EXTENSIONS

More terms from Ralf Stephan, Mar 30 2003

STATUS

approved