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A102286 Total number of odd blocks in all partitions of n-set. 4
1, 2, 7, 24, 96, 418, 1989, 10216, 56275, 330424, 2057672, 13532060, 93633021, 679473694, 5156626991, 40824399712, 336406367196, 2879570703510, 25557841113625, 234822774979908, 2230107923204443, 21861817965483016, 220940261740238140, 2299258336094622008 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) is also the number of set partitions of {1,2,...,n+1} in which the element 1 is in an even size block. - Geoffrey Critzer, Apr 02 2013

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..575

FORMULA

E.g.f: sinh(x)*exp(exp(x)-1).

EXAMPLE

a(3)=7 because we have (123), (1)/23, 12/(3), 13/(2), (1)/(2)/(3); the odd blocks are shown between parentheses.

MAPLE

G:=sinh(x)*exp(exp(x)-1): Gser:=series(G, x=0, 30): seq(n!*coeff(Gser, x^n), n=1..25); # Emeric Deutsch

# second Maple program:

with(combinat):

b:= proc(n, i) option remember; `if`(n=0 or i=1, [1, n],

       add((p->(p+[0, `if`(i::odd, j, 0)*p[1]]))(

       b(n-i*j, i-1))*multinomial(n, n-i*j, i$j)/j!, j=0..n/i))

    end:

a:= n-> b(n$2)[2]:

seq(a(n), n=1..30);  # Alois P. Heinz, Sep 16 2015

MATHEMATICA

Range[0, nn]! CoefficientList[

  D[Series[Exp[ (Cosh[x] - 1) + y Sinh[x]], {x, 0, nn}], y] /. y -> 1, x] (* Geoffrey Critzer, Aug 28 2012 *)

CROSSREFS

Cf. A005493, A000296.

Sequence in context: A150423 A150424 A150425 * A150426 A150427 A150428

Adjacent sequences:  A102283 A102284 A102285 * A102287 A102288 A102289

KEYWORD

easy,nonn

AUTHOR

Vladeta Jovovic, Feb 19 2005

EXTENSIONS

More terms from Emeric Deutsch, Mar 04 2005

STATUS

approved

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Last modified January 17 15:12 EST 2020. Contains 330958 sequences. (Running on oeis4.)