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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. 0

%I #5 Apr 04 2023 22:10:27

%S 1,5,6,11,76,105,501,505,506,605,756,826,1001,5941,10005,10505,12731,

%T 13921,50001,50005,50006,50105,50501,50505,50506,50605,60005,60505,

%U 88705,100001,118905,364231,592421,594941,684006,1000005,1000505,1050005,1050505,1355941

%N 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.

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

%o (Python)

%o from itertools import count, islice

%o def A362020_gen(startvalue=0): # generator of terms >= startvalue

%o return filter(lambda n:n%10 and n==int(''.join((s:=str(n**2))[len(s)&1^1::2])),count(max(startvalue,0)))

%o A362020_list = list(islice(A362020_gen(),50))

%Y Cf. A326418.

%K nonn,base

%O 1,2

%A _Chai Wah Wu_, Apr 04 2023

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Last modified May 17 07:06 EDT 2024. Contains 372579 sequences. (Running on oeis4.)