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 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). 0

%I

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

%T 2197,2025

%N 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).

%C 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.

%F 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]

%t 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}]

%Y Cf. A018226.

%K nonn,uned

%O 0,2

%A _Roger L. Bagula_, Apr 08 2006

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Last modified June 20 11:58 EDT 2021. Contains 345164 sequences. (Running on oeis4.)