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A053965
Squares composed of digits {4,7,9}.
1
4, 9, 49, 7744, 44944, 797449, 4794494447474944, 77777777797497997444, 749949999777797799497449749797947997449449477944777449
OFFSET
1,1
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
Cf. A053964.
Sequence in context: A053967 A028945 A086541 * A058444 A053925 A053943
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