OFFSET
1,1
LINKS
FORMULA
a(n) = A053964(n)^2.
MATHEMATICA
Table[Select[FromDigits/@Tuples[{4, 7, 9}, n], IntegerQ[Sqrt[#]]&], {n, 20}]//Flatten (* Harvey P. Dale, Mar 07 2018 *)
PROG
(Python)
from itertools import product
from sympy import integer_nthroot
A053965_list = []
for l in range(1, 21):
for p in product(*['479']*l):
n = int(''.join(p))
if integer_nthroot(n, 2)[1]:
A053965_list.append(n) # Chai Wah Wu, Apr 01 2021
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Patrick De Geest, Mar 15 2000
EXTENSIONS
More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 03 2005
a(9) from Zhao Hui Du, Feb 29 2024
STATUS
approved