OFFSET
0,2
LINKS
R. W. Grosse-Kunstleve, Table of n, a(n) for n = 0..1000
Sean A. Irvine, Generating Functions for Coordination Sequences of Zeolites, after Grosse-Kunstleve, Brunner, and Sloane
International Zeolite Association, Database of Zeolite Structures
Index entries for linear recurrences with constant coefficients, signature (1,-2,2,-2,3,-2,4,-3,4,-4,3,-4,2,-3,2,-2,2,-1,1).
FORMULA
From Chai Wah Wu, Feb 03 2021: (Start)
a(n) = a(n-1) - 2*a(n-2) + 2*a(n-3) - 2*a(n-4) + 3*a(n-5) - 2*a(n-6) + 4*a(n-7) - 3*a(n-8) + 4*a(n-9) - 4*a(n-10) + 3*a(n-11) - 4*a(n-12) + 2*a(n-13) - 3*a(n-14) + 2*a(n-15) - 2*a(n-16) + 2*a(n-17) - a(n-18) + a(n-19) for n > 19.
G.f.: -(x + 1)*(x^18 + 2*x^17 + 7*x^16 + 10*x^15 + 16*x^14 + 28*x^13 + 32*x^12 + 49*x^11 + 44*x^10 + 54*x^9 + 44*x^8 + 49*x^7 + 32*x^6 + 28*x^5 + 16*x^4 + 10*x^3 + 7*x^2 + 2*x + 1)/((x - 1)^3*(x^2 + 1)*(x^2 - x + 1)*(x^2 + x + 1)*(x^4 + x^3 + x^2 + x + 1)*(x^6 + x^5 + x^4 + x^3 + x^2 + x + 1)). (End)
CROSSREFS
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Mar 18 2018
STATUS
approved