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.

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

Offset

1,2

Links

Table of n, a(n) for n=1..46.

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