OFFSET
1,2
LINKS
Lars Blomberg, Table of n, a(n) for n = 1..10000
Andrew Weimholt, Middle digit in square numbers, Seqfan Mailing list, Dec 12 2016.
EXAMPLE
1^2 = (1), 72^2 = 101000(1)000000, 158^2 = 1100001(1)0000100
MATHEMATICA
a[n_]:=Part[IntegerDigits[n, 2], (Length[IntegerDigits[n, 2]] + 1)/2];
Select[Range[0, 293], OddQ[Length[IntegerDigits[#^2, 2]]] && a[#^2]==1 &] (* Indranil Ghosh, Mar 06 2017 *)
PROG
(PARI)
isok(k) = my(d=digits(k^2, 2)); (#d%2 == 1) && (d[#d\2 +1] == 1);
for(k=0, 293, if(isok(k)==1, print1(k, ", "))); \\ Indranil Ghosh, Mar 06 2017
(Python)
i=0
j=1
while i<=293:
n=str(bin(i**2)[2:])
l=len(n)
if l%2 and n[(l-1)//2]=="1":
print(str(i), end=", ")
j+=1
i+=1 # Indranil Ghosh, Mar 06 2017
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Lars Blomberg, Jan 07 2017
STATUS
approved