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A121726 Sum sequence A000522 then subtract 0,1,2,3,4,5,... 1
1, 2, 6, 21, 85, 410, 2366, 16065, 125665, 1112074, 10976174, 119481285, 1421542629, 18348340114, 255323504918, 3809950976993, 60683990530209, 1027542662934898, 18430998766219318, 349096664728623317 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also the row sums of A092271.

LINKS

Table of n, a(n) for n=1..20.

FORMULA

a(n) = A006231(n) + 1 = A002104(n) - (n-1). - Franklin T. Adams-Watters, Aug 29 2006

E.g.f.: exp(x)*(log(1/(1-x) - x + 1). - Geoffrey Critzer, Nov 07 2015

EXAMPLE

A000522 begins     1 2 5 16 65 326 ...

with sums          1 3 8 24 89 415 ...

so sequence begins 1 2 6 21 85 410 ...

MATHEMATICA

f[list_] :=Total[list]!/Apply[Times, list]/Apply[Times, Map[Length, Split[list]]!]; Table[Total[Map[f, Select[Partitions[n], Count[#, Except[1]] == 1 &]]] + 1, {n, 1, 20}] (* Geoffrey Critzer, Nov 07 2015 *)

PROG

(PARI) A000522(n)={ return( sum(k=0, n, n!/k!)) ; } A121726(n)={ return(sum(k=0, n-1, A000522(k))-n+1) ; } { for(n=1, 25, print1(A121726(n), ", ") ; ) ; } \\ R. J. Mathar, Sep 02 2006

CROSSREFS

Cf. A000522, A006231, A002104.

Sequence in context: A123922 A326276 A099947 * A090805 A150226 A326335

Adjacent sequences:  A121723 A121724 A121725 * A121727 A121728 A121729

KEYWORD

easy,nonn

AUTHOR

Alford Arnold, Aug 17 2006

EXTENSIONS

More terms from Franklin T. Adams-Watters, Aug 29 2006

More terms from R. J. Mathar, Sep 02 2006

STATUS

approved

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Last modified September 21 23:55 EDT 2019. Contains 327286 sequences. (Running on oeis4.)