The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A209344 T(n,k) is the number of n-bead necklaces labeled with numbers -k..k allowing reversal, with sum zero with no three beads in a row equal. 13
 1, 1, 2, 1, 3, 1, 1, 4, 4, 4, 1, 5, 7, 15, 5, 1, 6, 12, 35, 40, 14, 1, 7, 17, 72, 145, 146, 21, 1, 8, 24, 128, 400, 770, 514, 51, 1, 9, 31, 205, 883, 2698, 4029, 2032, 102, 1, 10, 40, 311, 1724, 7358, 18646, 22739, 8076, 249, 1, 11, 49, 448, 3045, 16968, 62853, 136000 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Table starts ..1....1.....1......1......1.......1.......1........1........1........1 ..2....3.....4......5......6.......7.......8........9.......10.......11 ..1....4.....7.....12.....17......24......31.......40.......49.......60 ..4...15....35.....72....128.....205.....311......448......618......829 ..5...40...145....400....883....1724....3045.....5026.....7827....11684 .14..146...770...2698...7358...16968...34720....64942...113288...186906 .21..514..4029..18646..62853..172610..409199...870122..1699831..3104474 .51.2032.22739.136000.563109.1830872.5016681.12099880.26438711.53392286 LINKS R. H. Hardin, Table of n, a(n) for n = 1..165 FORMULA Empirical for row n: n=2: a(k) = 2*a(k-1) - a(k-2). n=3: a(k) = 2*a(k-1) - 2*a(k-3) + a(k-4). n=4: a(k) = 3*a(k-1) - 3*a(k-2) + 2*a(k-3) - 3*a(k-4) + 3*a(k-5) - a(k-6). n=5: a(k) = 2*a(k-1) + a(k-2) - 3*a(k-3) - a(k-4) + a(k-5) + 3*a(k-6) - a(k-7) - 2*a(k-8) + a(k-9). n=6: a(k) = 4*a(k-1) - 5*a(k-2) + a(k-3) + a(k-4) + a(k-5) + a(k-6) - 5*a(k-7) + 4*a(k-8) - a(k-9). EXAMPLE Some solutions for n=6, k=8: .-4...-4...-4...-8...-7...-6...-6...-8...-7...-8...-7...-7...-8...-8...-8...-4 .-3...-3...-3...-3....0....1....1....0...-2....0....1...-2....3...-8...-4...-4 ..5...-1...-4....4...-4...-1....1....1....8....3....0....8...-4...-4....0...-2 .-2....3...-3....1....2....8....6....4...-5....5...-6....1....0....6....7....5 .-1...-1....6....3....3...-5...-6....0....5...-4....8...-7....6....7....3....7 ..5....6....8....3....6....3....4....3....1....4....4....7....3....7....2...-2 CROSSREFS Row 3 is A074148. Sequence in context: A099478 A133913 A209485 * A294099 A209115 A141412 Adjacent sequences:  A209341 A209342 A209343 * A209345 A209346 A209347 KEYWORD nonn,tabl AUTHOR R. H. Hardin, Mar 06 2012 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 21 21:32 EDT 2021. Contains 347605 sequences. (Running on oeis4.)