login
A230365
Squares representable as b! + triangular(c).
0
1, 4, 9, 16, 25, 121, 144, 196, 225, 256, 324, 441, 529, 900, 1296, 4096, 4489, 5041, 5476, 6561, 7056, 10609, 14884, 15625, 17956, 28561, 42025, 44100, 46656, 53361, 136900, 139129, 143641, 152100, 184041, 220900, 222784, 360000, 370881, 404496, 443556, 505521, 609961
OFFSET
1,2
PROG
(Python)
import math
factorials = [1] * 1024
f = 1
for n in range(2, 1025):
f *= n
factorials[n-1] = f
for n in range(1L<<30):
t = n*n
for a in factorials:
r = t - a
if r<0: break
b = int(math.sqrt(2*r))
if b*(b+1)==r*2:
print str(t)+', ',
break
CROSSREFS
KEYWORD
nonn
AUTHOR
Alex Ratushnyak, Oct 17 2013
STATUS
approved