A117580 A cubic quadratic sequence arranged so that the modulo-3 equals one cubic sequence is just ahead of the quadratic sequence (called here the Maestro sequence).

1, 9, 25, 27, 49, 81, 125, 169, 225, 343, 361, 441, 729, 729, 841, 1331, 1369, 1521, 2197, 2025

Offset: 0

Author

Roger L. Bagula, Apr 08 2006

Keywords

• nonn
• uned

Comments

Arranged so that they are near the Magic numbers (nuclear shell filling numbers): called Maestro as they have to be conducted like an orcestra to get them to behave this way.

Crossrefs

Cf. A018226.

Programs

Mathematica

g[n_] := (n - Floor[n/3])^3 /; Mod[n, 3] - 1 == 0 g[n_] := (2*n - 1)^2 /; (n < 4) g[n_] := (2*n - 1)^2 /; (n > 13) && (n < 17) g[n_] := (2*n - 3)^2 /; (n > 4) && (n < 13) g[n_] := (2*n + 3)^2 /; (n >= 17) && (n < 19) g[n_] := (2*n + 5)^2 /; (n >= 18) a=Table[g[n], {n, 1, 20}]

Formula

g[n_] := (n - Floor[n/3])^3 /; Mod[n, 3] - 1 == 0 g[n_] := (2*n - 1)^2 /; (n < 4) g[n_] := (2*n - 1)^2 /; (n > 13) && (n < 17) g[n_] := (2*n - 3)^2 /; (n > 4) && (n < 13) g[n_] := (2*n + 3)^2 /; (n >= 17) && (n < 19) g[n_] := (2*n + 5)^2 /; (n >= 18) a(n) = g[n]