A365820 Numbers with three or more digits such that every three consecutive digits are a nonzero square.

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

Links

Table of n, a(n) for n=1..46.

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

Adjacent sequences: A365817 A365818 A365819 * A365821 A365822 A365823

Keyword

nonn,base,fini,full

Author

Gonzalo Martínez, Dec 14 2023

Status

approved