cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-7 of 7 results.

A054745 Number of nonisomorphic binary n-state automata without output under input permutations.

Original entry on oeis.org

1, 1, 7, 74, 1474, 41876, 1540696, 68343112, 3540691525, 209612916303, 13957423192794, 1032436318269648, 83993175608894096, 7453446303042245261, 716451740543945788671, 74159075140708644544128, 8223831291824019614386868, 972718473204236819072891710
Offset: 0

Views

Author

Vladeta Jovovic, Apr 22 2000

Keywords

Comments

Also isomorphism classes of unordered pairs of endofunctions i.e. an unorder pair {f,g} of functions from {1,...,n} to itself. - Christian G. Bower, Dec 18 2003

References

  • F. Harary and E. Palmer, Graphical Enumeration, 1973.

Crossrefs

Programs

  • Maple
    with(numtheory):
    b:= proc(n, i) option remember; `if`(n=0, {0}, `if`(i<1, {},
          {seq(map(p-> p+j*x^i, b(n-i*j, i-1) )[], j=0..n/i)}))
        end:
    a:= proc(n) option remember; add(add(mul(mul(add(coeff(s, x, d)
          *d, d=divisors(ilcm(i, j)))^(igcd(i, j)*coeff(s, x, i)*
          coeff(t, x, j)), j=1..degree(t)), i=1..degree(s))
          /mul(i^coeff(t, x, i)*coeff(t, x, i)!, i=1..degree(t))
          /mul(i^coeff(s, x, i)*coeff(s, x, i)!, i=1..degree(s))
          , t=b(2$2)), s=b(n$2))
        end:
    seq(a(n), n=0..20);  # Alois P. Heinz, Aug 15 2014
  • Mathematica
    b[n_, i_] := b[n, i] = If[n==0, {0}, If[i<1, {}, Table[Map[Function[{p}, p + j*x^i], b[n - i*j, i-1]], {j, 0, n/i}] // Flatten // Union]];
    a[n_] := a[n] = Sum[Sum[Product[Product[With[{g = GCD[i, j]*Coefficient[s, x, i]*Coefficient[t, x, j]}, If[g==0, 1, Sum[Coefficient[s, x, d]*d, {d, Divisors[LCM[i, j]]}]^g]], {j, 1, Exponent[t, x]}], {i, 1, Exponent[s, x]}]/
    Product[i^Coefficient[t, x, i]Coefficient[t, x, i]!, {i, Exponent[t, x]}]/
    Product[i^Coefficient[s, x, i]Coefficient[s, x, i]!, {i, Exponent[s, x]}], {t, b[2, 2]}], {s, b[n, n]}];
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Mar 16 2015, after Alois P. Heinz, updated Jan 01 2021 *)

Formula

a(n) = sum {1*s_1+2*s_2+...=n, 1*t_1+2*t_2=2} (fixA[s_1, s_2, ...;t_1, t_2]/(1^s_1*s_1!*2^s_2*s_2!*...*1^t_1*t_1!*2^t_2*t_2!)) where fixA[...] = prod {i, j>=1} ( (sum {d|lcm(i, j)} (d*s_d))^(gcd(i, j)*s_i*t_j)). - Christian G. Bower, Dec 18 2003

Extensions

More terms from Alois P. Heinz, Aug 15 2014

A054746 Number of nonisomorphic connected binary n-state automata without output under input permutations.

Original entry on oeis.org

1, 6, 67, 1379, 40000, 1488212, 66468616, 3459744878, 205517092374, 13719689837415, 1016860316477931, 82855990193202263, 7361905026684383986, 708398087768889272827, 73390382551302560225067, 8144731151602797676232825, 963990026196934640329291135
Offset: 1

Views

Author

Vladeta Jovovic, Apr 22 2000

Keywords

Comments

Inverse Euler transform of A054745.

Examples

			There are 40000 nonisomorphic connected binary 5-state automata under input permutations.
		

References

  • F. Harary and E. Palmer, Graphical Enumeration, 1973.

Crossrefs

Extensions

More terms from Alois P. Heinz, Feb 20 2017

A000282 Finite automata.

Original entry on oeis.org

3, 70, 3783, 338475, 40565585, 6061961733, 1083852977811, 225615988054171, 53595807366038234, 14308700593468127485, 4241390625289880226714, 1382214286200071777573643, 491197439886557439295166226, 189044982636675290371386547592, 78334771617452038208125184627931, 34771576300926271400714044414858372
Offset: 1

Views

Author

Keywords

Comments

Given the name of A054747, another name for this sequence can be "Number of inequivalent n-state 2-input 2-output connected automata with respect to an input permutation." - Petros Hadjicostas, Mar 08 2021

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • PARI
    /* This program is a modification of Christian G. Bower's PARI program for the inverse Euler transform from the link above. */
    lista(nn) = {local(A=vector(nn+1)); for(n=1, nn+1, A[n]=if(n==1, 1, A054747(n-1))); local(B=vector(#A-1,n,1/n),C); A[1] = 1; C = log(Ser(A)); A=vecextract(A,"2.."); for(i=1, #A, A[i] = polcoeff(C,i)); A = dirdiv(A,B); } \\ Petros Hadjicostas, Mar 08 2021

Formula

Inverse Euler transform of A054747. - Petros Hadjicostas, Mar 08 2021

Extensions

More terms from Vladeta Jovovic, Apr 22 2000
Terms a(14)-a(16) from Petros Hadjicostas, Mar 08 2021

A054052 Number of nonisomorphic n-state automata with binary inputs and outputs.

Original entry on oeis.org

4, 136, 7860, 703760, 83731616, 12434579448, 2213014106124, 459106576445584, 108787771126443552, 28987989805582701000, 8579866813375037411844, 2792769757495835238342624, 991517773420290134796904064, 381299821992680629261308708504, 157894902912089771345216547890976, 70047508374342247037912201234627760
Offset: 1

Views

Author

Vladeta Jovovic, Apr 29 2000

Keywords

References

  • F. Harary and E. Palmer, Graphical Enumeration, 1973.

Crossrefs

Programs

  • PARI
    A054052(n) = {local(p=vector(n)); my(S=0, A() = prod(i=1, n, sumdiv(i, d, 2*d*p[d])^(2*p[i])), inc()=!forstep(i=n, 1, -1, p[i]n, p[i]=n); next(2))); t==n && S+ = A()/prod(i=1, n, i^p[i]*p[i]!)); S} \\ This is a modification of M. F. Hasler's PARI program from A002854. - Petros Hadjicostas, Mar 08 2021

Formula

a(n) = Sum_{1*s_1+2*s_2+...=n} fixA[s_1, s_2, ...]/(1^s_1*s_1!*2^s_2*s_2!*...), where fixA[s_1, s_2, ...] = Product_{i>=1} (Sum_{d|i} 2*d*s_d)^(2*s_i). - [Modified from Christian G. Bower's contribution in A054050 by Petros Hadjicostas, Mar 08 2021 using Theorem 6.1 in Harrison (1965) with k = 2 inputs and p = 2 outputs.]

Extensions

Terms a(14)-a(16) from Petros Hadjicostas, Mar 08 2021.

A054747 Number of inequivalent n-state 2-input 2-output automata with respect to an input permutation.

Original entry on oeis.org

3, 76, 4003, 352744, 41876694, 6217447912, 1106509486839, 229553329028386, 54393886281136386, 14493994916221695566, 4289933406949379595583, 1396384878753272032544946, 495758886710258565409900342, 190649910996342815795394676340, 78947451456044942567072721038672, 35023754187171124856459358053765838
Offset: 1

Views

Author

Vladeta Jovovic, Apr 22 2000

Keywords

References

  • F. Harary and E. Palmer, Graphical Enumeration, 1973.

Crossrefs

Euler transform of A000282.

Programs

  • PARI
    A054747(n)={local(p=vector(n)); local(q=matrix(2,2)); q[1,1] = 2; q[1,2] = 0; q[2,1]=0; q[2,2]=1; my(S=0, A() = sum(j=1, 2, prod(r=1, n, prod(s=1, 2, (2*sumdiv(lcm(r,s), d, if(d < n+1, d*p[d], 0)))^(p[r]*q[j,s]*gcd(r,s)))))/2,
    inc()=!forstep(i=n, 1, -1, p[i]n, p[i]=n); next(2))); t==n && S+ = A()/prod(i=1, n, i^p[i]*p[i]!)); S} \\ This is a modification of M. F. Hasler's PARI program from A002854. - Petros Hadjicostas, Mar 08 2021

Extensions

Terms a(14)-a(16) from Petros Hadjicostas, Mar 08 2021

A054748 Number of inequivalent n-state 1-input n-output automata.

Original entry on oeis.org

1, 6, 29, 209, 1652, 15981, 171837, 2060481, 26951143, 381398614, 5789262973, 93674732887, 1607249998772, 29114205685585, 554699253112833, 11079840198856480, 231366880421810416, 5038182952520057443, 114152394913959017721, 2685768694808159100283
Offset: 1

Views

Author

Vladeta Jovovic, Apr 22 2000

Keywords

References

  • F. Harary and E. Palmer, Graphical Enumeration, 1973.

Crossrefs

Formula

Euler transform of A054749.

Extensions

More terms from Sean A. Irvine, Feb 21 2022

A054742 Finite automata.

Original entry on oeis.org

2, 41, 1952, 172043, 20511924, 3058135804, 545880769246, 113492835877474, 26936031159146324, 7186257876123323136, 2129016419091882758064, 693526953186674417975860, 246375213208005330322801608, 94795009032593187381371471299, 39271207630529921493096501099998, 17428450442901657489782698628853383, 8249301503003544171210026750727519638
Offset: 1

Views

Author

Vladeta Jovovic, Apr 22 2000

Keywords

References

  • F. Harary and E. Palmer, Graphical Enumeration, 1973.

Crossrefs

Inverse Euler transform of A054732.

Programs

  • PARI
    /* This program is a modification of Christian G. Bower's PARI program for the inverse Euler transform from the link above. */
    lista(nn) = {local(A=vector(nn+1)); for(n=1, nn+1, A[n]=if(n==1, 1, A054732(n-1))); local(B=vector(#A-1, n, 1/n), C); A[1] = 1; C = log(Ser(A)); A=vecextract(A, "2.."); for(i=1, #A, A[i] = polcoeff(C, i)); A = dirdiv(A, B); } \\ Petros Hadjicostas, Mar 08 2021

Extensions

Terms a(14)-a(17) from Petros Hadjicostas, Mar 08 2021
Showing 1-7 of 7 results.