A212786 Half the number of 0..n arrays of length 7 with second differences nonzero.
21, 397, 4379, 22972, 91482, 284360, 764297, 1797975, 3883755, 7729696, 14517156, 25811656, 44024953, 72163603, 114677011, 176842932, 266174946, 391374778, 564396617, 798717009, 1112552471, 1525915970, 2065331568, 2759616340
Offset: 1
Keywords
Examples
Some solutions for n=5 ..3....1....0....1....3....3....1....0....1....0....4....3....0....1....4....0 ..3....1....0....4....5....2....0....5....3....1....0....1....1....1....4....5 ..5....0....4....2....1....2....2....3....3....5....1....3....5....5....0....2 ..1....1....3....1....2....4....2....2....1....3....4....0....4....1....1....3 ..5....0....0....5....1....0....5....4....3....4....4....4....1....2....1....5 ..1....4....4....4....2....0....5....3....4....0....3....2....0....4....5....0 ..4....4....3....1....0....5....1....5....1....0....5....5....0....0....2....1
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = -a(n-1) -a(n-2) +a(n-3) +4*a(n-4) +6*a(n-5) +7*a(n-6) +a(n-7) -6*a(n-8) -16*a(n-9) -20*a(n-10) -16*a(n-11) -2*a(n-12) +18*a(n-13) +32*a(n-14) +38*a(n-15) +24*a(n-16) +2*a(n-17) -27*a(n-18) -43*a(n-19) -43*a(n-20) -27*a(n-21) +2*a(n-22) +24*a(n-23) +38*a(n-24) +32*a(n-25) +18*a(n-26) -2*a(n-27) -16*a(n-28) -20*a(n-29) -16*a(n-30) -6*a(n-31) +a(n-32) +7*a(n-33) +6*a(n-34) +4*a(n-35) +a(n-36) -a(n-37) -a(n-38) -a(n-39)
Comments