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 A215985 Number of simple unlabeled graphs on n nodes with exactly 5 connected components that are trees or cycles. 3
 1, 1, 3, 6, 13, 26, 55, 112, 238, 510, 1117, 2498, 5712, 13322, 31643, 76455, 187382, 465393, 1168966, 2966298, 7594035, 19597653, 50933434, 133224112, 350477003, 926855665, 2462830565, 6572892862, 17612586165, 47369774428, 127841265076, 346120109957 (list; graph; refs; listen; history; text; internal format)
 OFFSET 5,3 LINKS Alois P. Heinz, Table of n, a(n) for n = 5..650 EXAMPLE a(7) = 3: .o-o o o.  .o-o o o.  .o o o o.           .|/     .  .|      .  .| |    .           .o o o  .  .o o o  .  .o o o  . MAPLE with(numtheory): b:= proc(n) option remember; local d, j; `if`(n<=1, n,       (add(add(d*b(d), d=divisors(j)) *b(n-j), j=1..n-1))/(n-1))     end: g:= proc(n) option remember; local k; `if`(n>2, 1, 0)+ b(n)-       (add(b(k)*b(n-k), k=0..n) -`if`(irem(n, 2)=0, b(n/2), 0))/2     end: p:= proc(n, i, t) option remember; `if`(n p(n, n, 5): seq(a(n), n=5..40); CROSSREFS Column k=5 of A215977. The labeled version is A215855. Sequence in context: A320733 A164991 A213255 * A215986 A215987 A215988 Adjacent sequences:  A215982 A215983 A215984 * A215986 A215987 A215988 KEYWORD nonn AUTHOR Alois P. Heinz, Aug 29 2012 STATUS approved

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Last modified March 28 15:06 EDT 2020. Contains 333089 sequences. (Running on oeis4.)