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Revision History for A301922

(Underlined text is an addition; strikethrough text is a deletion.)

Showing entries 1-10 | older changes
A301922 Regular triangle where T(n,k) is the number of unlabeled k-uniform hypergraphs spanning n vertices.
(history; published version)
#15 by Alois P. Heinz at Wed Aug 21 05:32:28 EDT 2019
STATUS

editing

approved

#14 by Alois P. Heinz at Wed Aug 21 05:19:57 EDT 2019
FORMULA

T(n,k) = A309858(n,k) - A309858(n-1,k). - Alois P. Heinz, Aug 21 2019

CROSSREFS

Cf. A003465, A055621, A298422, A298426, A299471, A301481, A301920, A306017-A306021, A309858.

#13 by Alois P. Heinz at Wed Aug 21 05:16:22 EDT 2019
MAPLE

g:= (l, i, n)-> `if`(i=0, `if`(n=0, [[]], []), [seq(map(x->

[x[], j], g(l, i-1, n-j))[], j=0..min(l[i], n))]):

h:= (p, v)-> (q-> add((s-> add(`if`(andmap(i-> irem(k[i], p[i]

/igcd(t, p[i]))=0, [$1..q]), mul((m-> binomial(m, k[i]*m

/p[i]))(igcd(t, p[i])), i=1..q), 0), t=1..s)/s)(ilcm(seq(

`if`(k[i]=0, 1, p[i]), i=1..q))), k=g(p, q, v)))(nops(p)):

b:= (n, i, l, v)-> `if`(n=0 or i=1, 2^((p-> h(p, v))([l[], 1$n]))

/n!, add(b(n-i*j, i-1, [l[], i$j], v)/j!/i^j, j=0..n/i)):

A:= proc(n, k) A(n, k):= `if`(k>n-k, A(n, n-k), b(n$2, [], k)) end:

T:= (n, k)-> A(n, k)-A(n-1, k):

seq(seq(T(n, k), k=1..n), n=1..9); # Alois P. Heinz, Aug 21 2019

STATUS

approved

editing

#12 by N. J. A. Sloane at Sat Aug 10 17:38:44 EDT 2019
STATUS

proposed

approved

#11 by Andrew Howroyd at Sat Aug 10 13:10:25 EDT 2019
STATUS

editing

proposed

#10 by Andrew Howroyd at Sat Aug 10 11:13:41 EDT 2019
PROG

(PARI)

permcount(v)={my(m=1, s=0, k=0, t); for(i=1, #v, t=v[i]; k=if(i>1&&t==v[i-1], k+1, 1); m*=t*k; s+=t); s!/m}

rep(typ)={my(L=List(), k=0); for(i=1, #typ, k+=typ[i]; listput(L, k); while(#L<k, listput(L, #L))); Vec(L)}

can(v, f)={my(d=1, u=v); while(d>0, u=vecsort(apply(f, u)); d=lex(u, v)); !d}

Q(n, k, perm)={my(t=0); forsubset([n, k], v, t += can(Vec(v), t->perm[t])); t}

U(n, k)={my(s=0); forpart(p=n, s += permcount(p)*2^Q(n, k, rep(p))); s/n!}

for(n=1, 10, for(k=1, n, print1(U(n, k)-U(n-1, k), ", ")); print) \\ Andrew Howroyd, Aug 10 2019

#9 by Andrew Howroyd at Fri Aug 09 22:28:46 EDT 2019
DATA

1, 1, 1, 1, 2, 1, 1, 7, 3, 1, 1, 23, 29, 4, 1, 1, 122, 2102, 150, 5, 1, 1, 888, 7011184, 7013164, 1037, 6, 1, 1, 11302, 1788775603336, 29281354507753848, 1788782615612, 12338, 7, 1, 1, 262322, 53304526022885280592, 234431745534048893449761040648512, 234431745534048922729326772799024, 53304527811667884902, 274659, 8, 1

LINKS

Andrew Howroyd, <a href="/A301922/b301922.txt">Table of n, a(n) for n = 1..91</a>

KEYWORD

nonn,tabl,more

EXTENSIONS

Terms a(16) and beyond from Andrew Howroyd, Aug 09 2019

STATUS

approved

editing

#8 by Susanna Cuyler at Tue Jun 19 22:13:37 EDT 2018
STATUS

proposed

approved

#7 by Gus Wiseman at Tue Jun 19 21:51:07 EDT 2018
STATUS

editing

proposed

#6 by Gus Wiseman at Tue Jun 19 21:50:54 EDT 2018
KEYWORD

nonn,tabl,changed,more

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Last modified August 18 09:22 EDT 2024. Contains 375264 sequences. (Running on oeis4.)