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 A176408 a(n) = (n+1)*(a(n-1) +a(n-2)) n>1, a(0)=1,a(1)=0 6
 1, 0, 3, 12, 75, 522, 4179, 37608, 376083, 4136910, 49642923, 645357996, 9035011947, 135525179202, 2168402867235, 36862848742992, 663531277373859, 12607094270103318 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS a(n) is one of two "basis" sequences for sequences of the form s(0)=a,s(1)=b,s(n)=(n+1)(s(n-1)+s(n-2)), n>1, the other being A006347. s(n) = a*a(n) + b* A006347(n+1). s(n) = 1/2*(b-2*a)(n+2)! +(3*a-b)*floor(((n+2)!+1)/e). LINKS Indranil Ghosh, Table of n, a(n) for n = 0..447 Michael Wallner, A bijection of plane increasing trees with relaxed binary trees of right height at most one, arXiv:1706.07163 [math.CO], 2017, Table 2 on p. 13. FORMULA a(n) = 3*floor(((n+2)!+1)/e) - (n+2)!. a(n) = 3* A000166(n+1) - (n+2)!, where A000166 are the subfactorial numbers. EXAMPLE a(2)= 3*9-24=3, a(3)= 3*44-120=12, a(4)= 3*265-720=75, ... MAPLE seq(3*floor(((n+2)!+1)/E) - (n+2)!, n=1..20); CROSSREFS Cf. A000166, A006347. Sequence in context: A317184 A342599 A291951 * A238630 A247330 A168366 Adjacent sequences: A176405 A176406 A176407 * A176409 A176410 A176411 KEYWORD nonn AUTHOR Gary Detlefs, Apr 16 2010 EXTENSIONS Data section corrected by Indranil Ghosh, Feb 15 2017 STATUS approved

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Last modified August 9 15:15 EDT 2024. Contains 375044 sequences. (Running on oeis4.)