login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A011843
a(n) = floor(binomial(n,5)/6).
1
0, 0, 0, 0, 0, 0, 1, 3, 9, 21, 42, 77, 132, 214, 333, 500, 728, 1031, 1428, 1938, 2584, 3391, 4389, 5608, 7084, 8855, 10963, 13455, 16380, 19792, 23751, 28318, 33562, 39556, 46376, 54105, 62832, 72649, 83657
OFFSET
0,8
LINKS
Index entries for linear recurrences with constant coefficients, signature (5, -10, 10, -5, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -5, 10, -10, 5, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 5, -10, 10, -5, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -5, 10, -10, 5, -1).
FORMULA
a(n) = +5*a(n-1) -10*a(n-2) +10*a(n-3) -5*a(n-4) +a(n-5) +a(n-18) -5*a(n-19) +10*a(n-20) -10*a(n-21) +5*a(n-22) -a(n-23) -a(n-36) +5*a(n-37) -10*a(n-38) +10*a(n-39) -5*a(n-40) +a(n-41) +a(n-54) -5*a(n-55) +10*a(n-56) -10*a(n-57) +5*a(n-58) -a(n-59). [R. J. Mathar, Apr 15 2010]
a(n) = floor(binomial(n+1,6)/(n+1)). [Gary Detlefs, Nov 23 2011]
MAPLE
seq(floor(binomial(n, 5)/6), n=0..38); # Zerinvary Lajos, Jan 12 2009
CROSSREFS
A column of triangle A011847.
Sequence in context: A161214 A354961 A213396 * A080549 A175006 A084569
KEYWORD
nonn
STATUS
approved