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 A274919 Sum of perimeters of the parts of the symmetric representation of sigma(n). 2
 4, 8, 12, 16, 16, 24, 20, 32, 32, 40, 28, 48, 32, 52, 52, 64, 40, 72, 44, 80, 72, 76, 52, 96, 68, 88, 88, 112 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) is also the number of toothpicks added at n-th stage in the toothpick structure of the symmetric representation of sigma in two quadrants (without the axis x and y). LINKS FORMULA a(n) = 4*A244361(n) = 2*A244363(n) = A244371(n)/2. EXAMPLE Illustration of a(9) = 32: .         12 .     _ _ _ _ _ .    |_ _ _ _ _| .               _ _ 8 .              |_  | .                |_|  _ .                    | | .                    | | .                    | |  12 .                    | | .                    |_| . For n = 9 the symmetric representation of sigma(9) = 13 has three parts of areas 5, 3, 5 respectively. The perĂ­meters of the parts are 12, 8 and 12 as shown above. The sum of the perimeters is 12 + 8 + 12 = 32, so a(9) = 32. CROSSREFS Cf. A000203, A196020, A236104, A237270, A237271, A237593, A244361, A244363, A244370, A244371, A245092, A262626. Sequence in context: A081747 A331061 A020647 * A196032 A130702 A053806 Adjacent sequences:  A274916 A274917 A274918 * A274920 A274921 A274922 KEYWORD nonn,more AUTHOR Omar E. Pol, Dec 11 2016 STATUS approved

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Last modified September 25 00:02 EDT 2020. Contains 337333 sequences. (Running on oeis4.)