OFFSET
0,2
COMMENTS
Corresponding triangular numbers t(n)=a(n)*a(n+1): 3, 15, 45, 153, 561, 1485, 3240, 10296, 21736, 46056, 127260, 189420, 271953, 574056, 1330896, 2197656, 3785376, 9058896, 15924546, 24890040, 37191000, ...
MATHEMATICA
a[0] = 1; a[n_] := a[n] = For[k = a[n-1]+1, True, k++, If[ IntegerQ[ Sqrt[8k*a[n-1]+1] ], Return[k] ] ]; Table[ Print[a[n]]; a[n], {n, 0, 42}] (* Jean-François Alcover, Sep 14 2012 *)
PROG
(Python)
a = 1
for n in range(55):
print(a, end=', ')
b = k = 0
while k<=a:
tn = b*(b+1)//2
k = 0
if tn%a==0:
k = tn // a
b += 1
a = k
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alex Ratushnyak, Aug 03 2012
STATUS
approved