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 A099958 (1/2)*number of distinct angular positions under which an observer positioned at the center of an edge of a square lattice can see the (2n)X(2n-1) points symmetrically surrounding his position. 3
 1, 5, 13, 23, 37, 55, 75, 95, 127, 157, 185, 227, 263, 305, 357, 403, 455, 511, 571, 631, 703, 769, 833, 923, 997, 1069, 1169, 1245, 1329, 1443, 1535, 1631, 1743, 1849, 1957, 2075, 2195, 2307, 2439, 2565, 2683, 2845, 2957, 3097, 3265, 3385 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA This is a bisection of A049690, that is, a(n) = Sum[k=1..2n+1, phi(2k)]. - Ralf Stephan, Nov 13, 2004. CROSSREFS See A099957 for further information. Cf. A049687, A049690, A190815. Sequence in context: A108195 A074798 A031336 * A213483 A049833 A083800 Adjacent sequences:  A099955 A099956 A099957 * A099959 A099960 A099961 KEYWORD nonn AUTHOR Hugo Pfoertner, Nov 13 2004 STATUS approved

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Last modified May 6 14:16 EDT 2021. Contains 343586 sequences. (Running on oeis4.)