This site is supported by donations to The OEIS Foundation.

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A209348 Number of 7-bead necklaces labelled with numbers -n..n allowing reversal, with sum zero with no three beads in a row equal 1
 21, 514, 4029, 18646, 62853, 172610, 409199, 870122, 1699831, 3104474, 5365417, 8858142, 14068115, 21614144, 32266607, 46975088, 66888951, 93389664, 128113109, 172986976, 230254897, 302518564, 392763779, 504407780, 641326401, 807907094 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Row 7 of A209344 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 3*a(n-1) -2*a(n-2) -a(n-3) +a(n-4) -2*a(n-5) +5*a(n-6) -5*a(n-7) +3*a(n-8) -3*a(n-10) +5*a(n-11) -5*a(n-12) +2*a(n-13) -a(n-14) +a(n-15) +2*a(n-16) -3*a(n-17) +a(n-18) EXAMPLE Some solutions for n=5 .-5...-4...-4...-5...-5...-4...-4...-3...-2...-2...-4...-4...-5...-5...-5...-4 .-5...-3....0...-4....0...-2...-3...-1...-1...-1...-3...-2...-2...-4...-3....1 .-1....5...-4....2....0...-2....1...-2...-1...-2....4....3...-1....0....5...-3 ..5....5....1....2....5....0....1....2....1...-1....1....3....5....4....2...-2 .-4...-3....2....1...-1....2....5....2...-1....3....5...-4....3....2...-2....1 ..5...-1....3...-1...-4....1....2....0....3....3...-4....0...-2....1....0....2 ..5....1....2....5....5....5...-2....2....1....0....1....4....2....2....3....5 CROSSREFS Sequence in context: A231542 A065921 A129993 * A095655 A221766 A080483 Adjacent sequences:  A209345 A209346 A209347 * A209349 A209350 A209351 KEYWORD nonn 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 | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .