OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harvey P. Dale)
EXAMPLE
For n = 5; a(3) = 3, a(4) = 5, a(5) = 7 before [(3+5)*(3+7)*(5+7)] / (3+5+7) = 64 (integer).
MATHEMATICA
nxt[{a_, b_}]:=Module[{h=b+1}, While[!IntegerQ[((a+b)(a+h)(b+h))/ (a+b+h)], h++]; {b, h}]; Transpose[NestList[nxt, {1, 2}, 40]][[1]] (* Harvey P. Dale, Dec 13 2012 *)
PROG
(Sage)
works = lambda a, h: ((a[-2]+a[-1])*(a[-2]+h)*(a[-1]+h)/(a[-2]+a[-1]+h)).is_integral()
a = [1, 2]
for n in range(3, 100):
a += [next(h for h in IntegerRange(a[-1]+1, infinity) if works(a, h))]
print(a)
# D. S. McNeil, Nov 28 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Nov 28 2010
EXTENSIONS
More terms from Harvey P. Dale, Dec 13 2012
STATUS
approved