OFFSET
0,2
COMMENTS
First 127 terms computed by Davide M. Proserpio using ToposPro.
LINKS
Davide M. Proserpio, Table of n, a(n) for n = 0..127
V. A. Blatov, A. P. Shevchenko, D. M. Proserpio, Applied Topological Analysis of Crystal Structures with the Program Package ToposPro, Cryst. Growth Des. 2014, 14, 3576-3586.
Reticular Chemistry Structure Resource (RCSR), The ftu tiling (or net)
FORMULA
The following is a conjectured recurrence, found by gfun, using the command rec:=gfun[listtorec](t1, a(n)); (where t1 is a list of the initial terms) suggested by Paul Zimmermann.
Note: this should not be used to extend the sequence.
0 = (-198*n^3-3934*n^2-22755*n)*a(n)+(-198*n^3-4330*n^2-26491*n)*a(n+1)+(-198*n^3-4726*n^2-30227*n)*a(n+2)+(-198*n^3-5122*n^2-33963*n)*a(n+3)+(-396*n^3-9452*n^2-60454*n)*a(n+4)
+(-396*n^3-10244*n^2-67926*n)*a(n+5)+(-396*n^3-11036*n^2-75398*n)*a(n+6)+(-198*n^3-7894*n^2-60115*n)*a(n+7)+(-198*n^3-8290*n^2-63851*n)*a(n+8)+(-4752*n^2-44832*n)*a(n+9)
+(-4752*n^2-44832*n)*a(n+10)+(198*n^3-818*n^2-22077*n)*a(n+11)+(198*n^3-422*n^2-18341*n)*a(n+12)+(396*n^3+3908*n^2+8150*n)*a(n+13)+(396*n^3+4700*n^2+15622*n)*a(n+14)+(396*n^3+5492*n^2+23094*n)*a(n+15)
+(198*n^3+2350*n^2+7811*n)*a(n+16)+(198*n^3+2746*n^2+11547*n)*a(n+17)+(198*n^3+3142*n^2+15283*n)*a(n+18)+(198*n^3+3538*n^2+19019*n)*a(n+19),
with a(0) = 1, a(1)= 4, a(2) = 9, a(3) = 16, a(4) = 26, a(5) = 40, a(6) = 57, a(7) = 78, a(8) = 103, a(9) = 130, a(10) = 159, a(11) = 190, a(12) = 224, a(13) = 262, a(14) = 305, a(15) = 353, a(16) = 405, a(17) = 458, a(18) = 511, a(19) = 566.
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Feb 22 2018
STATUS
approved