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 A155877 Sums of three Fermat numbers. 4
 9, 11, 13, 15, 23, 25, 27, 37, 39, 51, 263, 265, 267, 277, 279, 291, 517, 519, 531, 771, 65543, 65545, 65547, 65557, 65559, 65571, 65797, 65799, 65811, 66051, 131077, 131079, 131091, 131331, 196611, 4294967303, 4294967305, 4294967307 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..38. Eric Weisstein's World of Mathematics, Generalized Fermat Number. FORMULA {(2^(2^a) + 1) + (2^(2^b) + 1) + (2^(2^c) + 1) = {A000215(a) + A000215(b) + A000215(c)}. EXAMPLE a(1) = 3 + 3 + 3 = 9. a(2) = 3 + 3 + 5 = 11. a(3) = 3 + 5 + 5 = 13. a(4) = 5 + 5 + 5 = 15. a(5) = 3 + 3 + 17 = 23. a(6) = 3 + 5 + 17 = 25. a(7) = 5 + 5 + 17 = 27. a(8) = 3 + 17 + 17 = 37. a(9) = 5 + 17 + 17 = 39. a(10) = 17 + 17 + 17 = 51. a(11) = 3 + 3 + 257 = 263. CROSSREFS Cf. A000215, A019434, A050922, A051179, A059919, A063486, A073617, A078303, A078304, A085866. Sequence in context: A123760 A289686 A251394 * A214865 A225557 A120177 Adjacent sequences: A155874 A155875 A155876 * A155878 A155879 A155880 KEYWORD nonn AUTHOR Jonathan Vos Post, Jan 29 2009 EXTENSIONS More terms from R. J. Mathar, Feb 06 2009 STATUS approved

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Last modified September 21 12:15 EDT 2023. Contains 365501 sequences. (Running on oeis4.)