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A005897 a(n) = 6*n^2 + 2 for n > 0, a(0)=1.
(Formerly M4497)
522
1, 8, 26, 56, 98, 152, 218, 296, 386, 488, 602, 728, 866, 1016, 1178, 1352, 1538, 1736, 1946, 2168, 2402, 2648, 2906, 3176, 3458, 3752, 4058, 4376, 4706, 5048, 5402, 5768, 6146, 6536, 6938, 7352, 7778, 8216, 8666, 9128, 9602, 10088, 10586 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Number of points on surface of 3-dimensional cube in which each face has a square grid of dots drawn on it (with n+1 points along each edge, including the corners).

Coordination sequence for b.c.c. lattice.

Binomial transform of [1, 7, 11, 1, -1, 1, -1, 1, ...]. - Gary W. Adamson, Oct 22 2007

First differences of A005898 centered cube numbers: n^3 + (n+1)^3. - Jonathan Vos Post, Feb 06 2011

Apart from the first term, numbers of the form (r^2+2*s^2)*n^2+2 = (r*n)^2+(s*n-1)^2+(s*n+1)^2: in this case is r=2, s=1. After 8, all terms are in A000408. - Bruno Berselli, Feb 07 2012

For n > 0, the sequence of last digits (i.e., a(n) mod 10) is (8, 6, 6, 8, 2) repeating forever. - M. F. Hasler, Apr 05 2016

Number of cubes of edge length 1 required to make a hollow cube of edge length n+1. - Peter M. Chema, Apr 01 2017

REFERENCES

H. S. M. Coxeter, "Polyhedral numbers," in R. S. Cohen et al., editors, For Dirk Struik. Reidel, Dordrecht, 1974, pp. 25-35.

Gmelin Handbook of Inorg. and Organomet. Chem., 8th Ed., 1994, TYPIX search code (194) hP4

R. W. Marks and R. B. Fuller, The Dymaxion World of Buckminster Fuller. Anchor, NY, 1973, p. 46.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

B. K. Teo and N. J. A. Sloane, Magic numbers in polygonal and polyhedral clusters, Inorgan. Chem. 24 (1985), 4545-4558.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..10000

R. W. Grosse-Kunstleve, Coordination Sequences and Encyclopedia of Integer Sequences

R. W. Grosse-Kunstleve, G. O. Brunner and N. J. A. Sloane, Algebraic Description of Coordination Sequences and Exact Topological Densities for Zeolites, Acta Cryst., A52 (1996), pp. 879-889.

Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992.

Simon Plouffe, 1031 Generating Functions and Conjectures, Université du Québec à Montréal, 1992.

Index entries for sequences related to b.c.c. lattice

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

FORMULA

G.f.: (1+x)*(1+4*x+x^2)/(1-x)^3. - Simon Plouffe (see MAPLE line)

a(0) = 1, a(n) = (n+1)^3 - (n-1)^3. - Ilya Nikulshin (ilyanik(AT)gmail.com), Aug 11 2009

a(0)=1, a(1)=8, a(2)=26, a(3)=56; for n>3, a(n) = 3*a(n-1)-3*a(n-2)+a(n-3). - Harvey P. Dale, Oct 25 2011

a(n) = A033581(n) + 2. - Reinhard Zumkeller, Apr 27 2014

EXAMPLE

For n = 1 we get the 8 corners of the cube; for n = 2 each face has 9 points, for a total of 8 + 12 + 6 = 26.

MAPLE

A005897:=-(z+1)*(z**2+4*z+1)/(z-1)**3; # conjectured (correctly) by Simon Plouffe in his 1992 dissertation

MATHEMATICA

Join[{1}, 6Range[50]^2+2] (* or *) Join[{1}, LinearRecurrence[{3, -3, 1}, {8, 26, 56}, 50]] (* Harvey P. Dale, Oct 25 2011 *)

PROG

(MAGMA) [1] cat [6*n^2 + 2: n in [1..50]]; // Vincenzo Librandi, Oct 26 2011

(PARI) a(n)=if(n, 6*n^2+2, 1) \\ Charles R Greathouse IV, Mar 06 2014

(Haskell) a005897 n = if n == 0 then 1 else 6 * n ^ 2 + 2 -- Reinhard Zumkeller, Apr 27 2014

CROSSREFS

Cf. A000578, A206399.

Sequence in context: A126264 A225274 A085690 * A215097 A111694 A129111

Adjacent sequences:  A005894 A005895 A005896 * A005898 A005899 A005900

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane, R. W. Grosse-Kunstleve (rwgk(AT)cci.lbl.gov)

STATUS

approved

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Last modified June 27 15:18 EDT 2017. Contains 288790 sequences.