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A365820
Numbers with three or more digits such that every three consecutive digits are a nonzero square.
0
100, 121, 144, 169, 196, 225, 256, 289, 324, 361, 400, 441, 484, 529, 576, 625, 676, 729, 784, 841, 900, 961, 1001, 1004, 1009, 1441, 1961, 2256, 4001, 4004, 4009, 4841, 6256, 7841, 9001, 9004, 9009, 10016, 10049, 40016, 40049, 90016, 90049, 100169, 400169, 900169
OFFSET
1,1
EXAMPLE
2256 is in this sequence because 225 and 256 are both squares.
PROG
(Python)
from math import isqrt
def ok(n): s = str(n); return len(s)>=3 and all((x:=int(s[i:i+3]))>0 and isqrt(x)**2==x for i in range(len(s)-2))
print([k for k in range(10**6) if ok(k)]) # Michael S. Branicky, Dec 14 2023
CROSSREFS
Cf. A000290, A291334 (2 or more digits).
Sequence in context: A328864 A143919 A071987 * A095633 A228103 A331543
KEYWORD
nonn,base,fini,full
AUTHOR
Gonzalo Martínez, Dec 14 2023
STATUS
approved