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 A007439 Number of planted trees: all sub-rooted trees from any node are identical; non-root, non-leaf nodes an even distance from the root are of degree 2. (Formerly M0301) 7
 1, 1, 1, 2, 2, 4, 3, 7, 4, 11, 6, 15, 7, 24, 8, 29, 12, 40, 13, 51, 14, 68, 19, 76, 20, 107, 23, 116, 29, 147, 30, 175, 31, 215, 39, 229, 45, 297, 46, 312, 55, 387, 56, 435, 57, 513, 73, 534, 74, 670, 78, 705, 92, 823, 93, 897, 102, 1051, 117, 1082 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS T. D. Noe, Table of n, a(n) for n=1..1000 N. J. A. Sloane, Transforms FORMULA a(n+2) = Sum a(k), k|n. Shifts left two places under inverse Moebius transformation. MATHEMATICA a[n_] := a[n] = Sum[a[k], {k, Divisors[n-2]}]; a[1] = a[2] = 1; Table[a[n], {n, 1, 60}] (* Jean-François Alcover, May 15 2013 *) PROG (Haskell) a007439 n = a007439_list !! (n-1) a007439_list = 1 : 1 : f 2 where    f x = (sum \$ map a007439 \$ a027750_row (x - 1)) : f (x + 1) -- Reinhard Zumkeller, Dec 20 2014 CROSSREFS Cf. A003238, A007562. Cf. A027750. Sequence in context: A057449 A286931 A265701 * A238622 A096441 A100824 Adjacent sequences:  A007436 A007437 A007438 * A007440 A007441 A007442 KEYWORD nonn,nice,eigen,look AUTHOR EXTENSIONS New description from Christian G. Bower, Oct 15 1998. STATUS approved

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Last modified October 19 17:55 EDT 2018. Contains 316376 sequences. (Running on oeis4.)