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 A078942 Flipping burnt pancakes. Given a sorted stack of n burnt pancakes of different sizes (smallest on top, ..., largest at the bottom), each with its burnt side up, a(n) is the number of spatula flips needed to restore them to their initial order but with the burnt sides down. 2
 1, 4, 6, 8, 10, 12, 14, 15, 17, 18, 19, 21, 22, 23, 24, 26, 28, 29 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS In a 'spatula flip', a spatula is inserted below any pancake and all pancakes above the spatula are lifted and replaced in reverse order. It is conjectured that this initial configuration is a worst case for the general problem of sorting burnt pancakes. If so, then this sequence is identical to A078941. REFERENCES David S. Cohen and Manuel Blum, "On the problem of sorting burnt pancakes", Discrete Applied Math., 61 (1995) 105-120. LINKS Douglas B. West, The Pancake Problems (1975, 1979, 1973) - From N. J. A. Sloane, Jul 26 2012 FORMULA a(n) <= A078941(n). a(n+1) <= a(n) + 2. 3n/2 <= a(n) <= 47n/30 + c for some constant c. CROSSREFS Cf. A078941, A058986. Sequence in context: A272601 A322368 A078941 * A248419 A186389 A039767 Adjacent sequences:  A078939 A078940 A078941 * A078943 A078944 A078945 KEYWORD nonn,more AUTHOR Dean Hickerson, Dec 18 2002 STATUS approved

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Last modified April 22 14:33 EDT 2021. Contains 343177 sequences. (Running on oeis4.)