A343726 - OEIS

%I #19 May 23 2021 00:19:22

%S 0,4,16,25,36,49,81,121,169,196,361,529,576,729,961,1156,1369,1521,

%T 1936,3136,3721,3969,5329,5776,5929,7396,7569,7921,15129,15376,17161,

%U 17956,19321,31329,35721,51529,53361,57121,59536,97969,111556,113569,119716,131769

%N Squares with exactly one even digit.

%C The even digit is always one of the last two digits.

%C The only squares with no digits even are the one-digit odd squares 1 and 9.

%H Jianing Song, <a href="/A343726/b343726.txt">Table of n, a(n) for n = 1..10000</a>

%F Intersection of A000290 and A118070.

%p q:= n-> (l-> is(add(i mod 2, i=l)=nops(l)-1))(convert(n, base, 10)):

%p select(q, [i^2$i=0..400])[];  # _Alois P. Heinz_, May 22 2021

%t Select[Range[0, 400]^2, Count[IntegerDigits[#], _?EvenQ] == 1 &] (* _Amiram Eldar_, May 21 2021 *)

%o (Python)

%o def ok(sq): return sum(d in "02468" for d in str(sq)) == 1

%o def aupto(limit):

%o   sqs = (i*i for i in range(int(limit**.5)+2) if i*i <= limit)

%o   return list(filter(ok, sqs))

%o print(aupto(131769)) # _Michael S. Branicky_, May 20 2021

%o (PARI) isA343726(n) = if(issquare(n) && (n!=0), my(d=digits(n)); #d - vecsum(d%2) == 1, n==0) \\ _Jianing Song_, May 22 2021

%Y Cf. A000290, A030098, A118070, A343724, A343725.

%K nonn,base

%O 1,2

%A _Jon E. Schoenfield_, May 19 2021