OFFSET
1,1
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10000
FORMULA
{m: A177025(m)=2}.
EXAMPLE
6 is a triangular and a hexagonal number, but is not any other k-gonal number.
PROG
(PARI) lista(nn) = {for (n=1, nn, if (sum(k=3, n, ispolygonal(n, k)) == 2, print1(n, ", ")); ); } \\ Michel Marcus, Mar 25 2015
(Python)
A177029_list = []
for m in range(1, 10**4):
n, c = 3, 0
while n*(n+1) <= 2*m:
if not 2*(n*(n-2) + m) % (n*(n - 1)):
c += 1
if c > 1:
break
n += 1
if c == 1:
A177029_list.append(m) # Chai Wah Wu, Jul 28 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, May 01 2010
EXTENSIONS
Extended by R. J. Mathar, Aug 15 2010
STATUS
approved