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 A237502 Number of binary strings of length 2n which contain the ones' complements and the reversals of each of their two halves. 2
 2, 6, 8, 16, 26, 46, 72, 116, 184, 288, 434, 646, 980, 1444, 2122, 3066, 4500, 6452, 9362, 13294 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE The two halves of 1000111000 are 10001 and 11000. Their reversals are 10001 and 00011, and their complements are 01110 and 00111 and all are substrings of 1000111000. Since there are 25 other strings of length 2*5 with this property, a(5) = 26. MATHEMATICA sQ[L_, {s__}] := MatchQ[L, {___, s, ___}]; a[n_] := Length@ Select[ Tuples[{0, 1}, 2*n], sQ[#, Reverse[Take[#, n]]] && sQ[#, Reverse[Take[#, -n ]]] && sQ[#, 1 - Take[#, n]] && sQ[#, 1 - Take[#, -n]] &]; Array[a, 8] CROSSREFS Cf. A237500, A237501. Sequence in context: A266074 A191822 A238549 * A279726 A137848 A182629 Adjacent sequences:  A237499 A237500 A237501 * A237503 A237504 A237505 KEYWORD nonn AUTHOR Giovanni Resta, Feb 08 2014 STATUS approved

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Last modified October 17 03:38 EDT 2019. Contains 328106 sequences. (Running on oeis4.)