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 A334307 Number of graceful labelings for the complete tripartite graph K_1,1,n. 3
 12, 32, 168, 1152, 9600, 97920, 1491840, 21127680, 377395200, 7605964800, 164457216000, 3935477145600, 102571486617600, 2858053098700800, 85725900868608000, 2745404797943808000, 93266934645620736000, 3356738924418367488000, 127589166595209166848000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Except for n = 2, a(n) = A333728(n+2) up to at least n = 6. LINKS Don Knuth, Table of n, a(n) for n = 1..48 Eric Weisstein's World of Mathematics, Complete Tripartite Graph Eric Weisstein's World of Mathematics, Graceful Labeling FORMULA If n>1, a(n) = 4*A339891(n)*n!. - Don Knuth, Dec 21 2020. CROSSREFS Cf. A333728 (maximum number of graceful labelings for an n-node simple graph), A339891. Sequence in context: A268769 A045669 A045660 * A192213 A050690 A079561 Adjacent sequences: A334304 A334305 A334306 * A334308 A334309 A334310 KEYWORD nonn AUTHOR Eric W. Weisstein, Apr 24 2020 EXTENSIONS a(8) and a(9) from Pontus von Brömssen, Jul 25 2020 Terms a(10) and beyond from Don Knuth, Dec 21 2020 STATUS approved

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Last modified May 28 04:05 EDT 2023. Contains 362992 sequences. (Running on oeis4.)