A194069 1+floor((2/3)*n^2).

1, 3, 7, 11, 17, 25, 33, 43, 55, 67, 81, 97, 113, 131, 151, 171, 193, 217, 241, 267, 295, 323, 353, 385, 417, 451, 487, 523, 561, 601, 641, 683, 727, 771, 817, 865, 913, 963, 1015, 1067, 1121, 1177, 1233, 1291, 1351, 1411

Offset: 1

Author

Clark Kimberling, Aug 14 2011

Keywords

• nonn

Crossrefs

Cf. A194070 (natural fractal sequence),

A194071 (natural fractal interspersion).

Programs

Mathematica

c[k_]:=1+Floor[(2/3)k^2]; c=Table[c[k],{k,1,90}]

Formula

a(n)=1+floor(2*n^2/3).

a(n) = 1 +A030511(n+1). - R. J. Mathar, Aug 25 2011