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 A127389 Number of fixed points in range [A014137(n-1)..A014138(n-1)] of permutations A127377/A127378 and A127387. 5
 1, 1, 0, 1, 2, 4, 10, 23, 56, 138, 344, 870, 2220, 5716, 14828, 38717, 101682, 268416, 711810, 1895432, 5066030, 13586082, 36547534, 98593064, 266661162, 722953814, 1964358938, 5348367006, 14589803090, 39870312218, 109136843138 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 LINKS FORMULA G.f. satisfies: A(x) = (1 + x*A(x)^2)*(1+x)/(1+x+2*x^2). PROG (PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=(1 + x*A^2)*(1+x)/(1+x+2*x^2)); polcoeff(A, n)} CROSSREFS This is INVERTi transform of A086625 (appropriately shifted). I.e. INVERT([1, 1, 0, 1, 2, 4, 10, 23, 56, 138, 344, 870, 2220, 5716]) gives: 1, 2, 3, 6, 12, 26, 59, 138, 332, 814, 2028, 5118, ... (beginning of A086625) Sequence in context: A191693 A238436 A137681 * A152173 A032171 A127713 Adjacent sequences:  A127386 A127387 A127388 * A127390 A127391 A127392 KEYWORD nonn AUTHOR Antti Karttunen, Jan 16 2007. Generating function, PARI-program and most of the terms supplied by Paul D. Hanna, Jan 15 2007. STATUS approved

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Last modified September 28 09:16 EDT 2021. Contains 347714 sequences. (Running on oeis4.)