A162519 -id:A162519 - cp's OEIS frontend

A162518 Characteristic function of magic numbers A018226: 1 if n is a magic number else 0.

0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1

Offset: 1

Omar E. Pol, Jul 07 2009

nonn

Sequence related to atomic nuclei.

Antti Karttunen, Table of n, a(n) for n = 1..10000
Index entries for characteristic functions

Cf. A018226, A130517, A130556, A130598, A130602, A162519, A162521, A162522, A162523, A162524, A162525.

A162518(n) = if(n<1, 0, polcoeff( x^126+x^82+x^50+x^28+x^20+x^8+x^2, n)); \\ Antti Karttunen, Dec 24 2018, after code in A089011

Data section extended up to a(126) by Antti Karttunen, Dec 24 2018

A162626 If 0 <= n <= 3 then a(n) = n(n+1)(n+2)/3, if n >= 4 then a(n) = n(n^2+5)/3.

Original entry on oeis.org

0, 2, 8, 20, 28, 50, 82, 126, 184, 258, 350, 462, 596, 754, 938, 1150, 1392, 1666, 1974, 2318, 2700, 3122, 3586, 4094, 4648, 5250, 5902, 6606, 7364, 8178, 9050, 9982, 10976, 12034, 13158, 14350, 15612, 16946, 18354, 19838, 21400, 23042, 24766, 26574

Offset: 0

Omar E. Pol, Jul 07 2009, Jul 13 2009

One way to generalize the magic number sequence in A018226.

See also A130598 and A162630.

Cf. A007290, A018226, A033547, A130598, A162518, A162519, A162521, A162522, A162523, A162524, A162525, A162630.

From Daniel Forgues, May 03 2011: (Start)
If 0 <= n <= 3 then a(n) = 2 T_n, otherwise a(n) = 2 (T_n - t_{n-1}), where T_n is the n-th tetrahedral number, t_n the n-th triangular number.
G.f.: (2*x*(1 - 6*x^3 + 14*x^4 - 11*x^5 + 3*x^6))/(1 - x)^4, n >= 0.
(End)
a(n) = n*(n^2+5)/3 + (4*n-6)*A171386(n). - Omar E. Pol, Aug 14 2013

Edited by N. J. A. Sloane, Jul 18 2009

cp's OEIS Frontend

A162518 Characteristic function of magic numbers A018226: 1 if n is a magic number else 0.

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