A362020 Nonnegative numbers k not ending in 0 such that, in decimal representation, the subsequence of digits of k^2 occupying an odd position is equal to the digits of k.

1, 5, 6, 11, 76, 105, 501, 505, 506, 605, 756, 826, 1001, 5941, 10005, 10505, 12731, 13921, 50001, 50005, 50006, 50105, 50501, 50505, 50506, 50605, 60005, 60505, 88705, 100001, 118905, 364231, 592421, 594941, 684006, 1000005, 1000505, 1050005, 1050505, 1355941

Offset

1,2

Comments

Subsequence of A326418. No term starts with the digit 2.

Links

Table of n, a(n) for n=1..40.

Prog

(Python)
from itertools import count, islice
def A362020_gen(startvalue=0): # generator of terms >= startvalue
    return filter(lambda n:n%10 and n==int(''.join((s:=str(n**2))[len(s)&1^1::2])), count(max(startvalue, 0)))
A362020_list = list(islice(A362020_gen(), 50))

Crossrefs

Cf. A326418.

Sequence in context: A332523 A041227 A042183 * A328544 A041939 A177714

Adjacent sequences: A362017 A362018 A362019 * A362021 A362022 A362023

Keyword

nonn,base

Author

Chai Wah Wu, Apr 04 2023

Status

approved