The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A262068 Number of binary strings of length 2n that can be written as the concatenation of one or more squares. 1
 1, 2, 6, 22, 76, 268, 926, 3250, 11328, 39658, 138534, 484364, 1693078, 5918780, 20690230, 72328158, 252841374, 883869956, 3089791576, 10801141656 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS By a "square" we mean a word of the form xx, where x is a string, like the English word "murmur". a(0)=1 is by convention. - N. J. A. Sloane, Sep 17 2015 LINKS EXAMPLE For n = 2 the six words are 0000, 0011, 0101, and their complements. MAPLE for n from 1 to 13 do B[n]:= convert(map(t-> t||t, StringTools:-Generate(n, "01")), set); od: C[0]:= {""}: for n from 1 to 13 do   C[n]:= {seq(seq(seq(cat(s, t), s=B[i]), t = C[n-i]), i=1..n)}; od: seq(nops(C[n]), n=0..13); # Robert Israel, Sep 17 2015 PROG (Python) # MS() in A262278 from numba import njit @njit()  # comment out for n >= 32 def a(n):   if n == 0: return 1  # by convention   s = 0   for b in range(int(2**(2*n-1))):     s += MS(b, n) >= 1   return 2*s print([a(n) for n in range(10)]) # Michael S. Branicky, Dec 29 2020 CROSSREFS Cf. A262278. Sequence in context: A109194 A014334 A107239 * A148496 A217528 A181367 Adjacent sequences:  A262065 A262066 A262067 * A262069 A262070 A262071 KEYWORD nonn,more AUTHOR Jeffrey Shallit, Sep 17 2015 EXTENSIONS a(14)-a(19) from Lars Blomberg, Feb 03 2019 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 9 03:35 EDT 2021. Contains 343685 sequences. (Running on oeis4.)