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 A279430 Numbers k such that k^2 has an odd number of digits in base 2 and the middle digit is 0. 14
 0, 2, 4, 5, 8, 9, 10, 16, 17, 18, 19, 22, 32, 33, 34, 35, 36, 37, 40, 41, 44, 64, 65, 66, 67, 68, 69, 70, 71, 76, 77, 80, 81, 84, 85, 87, 90, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 144, 145, 146, 147, 151, 152, 153, 156, 157, 160, 161, 164 (list; graph; refs; listen; history; text; internal format)
 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. MATHEMATICA a[n_]:=Part[IntegerDigits[n, 2], (Length[IntegerDigits[n, 2]]+1)/2]; Select[Range[0, 164], OddQ[Length[IntegerDigits[#^2, 2]]] && a[#^2]==0 &] (* Indranil Ghosh, Mar 06 2017 *) PROG (PARI) isok(k) = my(d=digits(k^2, 2)); (#d%2 == 1) && (d[#d\2 +1] == 0); for(k=0, 164, if(k==0 || isok(k)==1, print1(k, ", "))); \\ Indranil Ghosh, Mar 06 2017 (Python) i=0 j=1 while i<=164: ....n=str(bin(i**2)[2:]) ....l=len(n) ....if l%2==1 and n[(l-1)/2]=="0": ........print (str(i))+", ", ........j+=1 ....i+=1 # Indranil Ghosh, Mar 06 2017 CROSSREFS Cf. A279431. See A279420-A279429 for a base-10 version. Sequence in context: A045702 A005658 A166021 * A003714 A010402 A010443 Adjacent sequences:  A279427 A279428 A279429 * A279431 A279432 A279433 KEYWORD nonn,base,easy AUTHOR Lars Blomberg, Jan 07 2017 STATUS approved

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Last modified October 23 02:28 EDT 2018. Contains 316518 sequences. (Running on oeis4.)