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 1-3 of 3 results.

A005736 Number of degenerate fanout-free Boolean functions of n variables using And, Or and Not gates.

Original entry on oeis.org

0, 2, 6, 32, 314, 4892, 104518, 2814520, 91069042, 3434371508, 147755228670, 7137203824016, 382309275191786, 22484502178536140, 1440083130444110134, 99761235465965943400, 7431676025141300550370, 592372327653418546022756
Offset: 0

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Author

Keywords

References

  • J. P. Hayes, Enumeration of fanout-free Boolean functions, J. ACM, 23 (1976), 700-709.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Formula

a(n) = Sum_{k=0..n-1} binomial(n, k) * s(k) where s(0)=2 and s(n) = A005640(n + 1) otherwise. - Sean A. Irvine, Jul 21 2016
a(n) = A005737(n) - A224766(n). - Andrew Howroyd, Mar 29 2025

Extensions

More terms from Sean A. Irvine, Jul 21 2016
Name clarified by Andrew Howroyd, Apr 03 2025

A225171 Triangle read by rows: T(n,k), 1 <= k <= n, is the number of non-degenerate fanout-free Boolean functions of n variables having AND rank k.

Original entry on oeis.org

2, 4, 4, 32, 24, 8, 416, 304, 96, 16, 7552, 5440, 1760, 320, 32, 176128, 125824, 41280, 8000, 960, 64, 5018624, 3566080, 1180928, 237440, 31360, 2688, 128, 168968192, 119614464, 39875584, 8212736, 1146880, 111104, 7168, 256, 6563282944, 4633387008, 1552320512, 325183488, 47104512, 4902912, 365568, 18432, 512
Offset: 1

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Author

N. J. A. Sloane, Apr 30 2013

Keywords

Comments

Also the Bell transform of A225170. For the definition of the Bell transform see A264428. - Peter Luschny, Jan 29 2016

Examples

			Triangle begins
2,
4,4,
32,24,8,
416,304,96,16,
7552,5440,1760,320,32,
176128,125824,41280,8000,960,64,
5018624,3566080,1180928,237440,31360,2688,128,
168968192,119614464,39875584,8212736,1146880,111104,7168,256,
...
		

Crossrefs

Columns give A225170 (or A005172), A005756, A224767, A224768.
Row sums are A224766.

Programs

  • Maple
    # Function BellMatrix defined in A264428.
    BellMatrix(n -> `if`(n=0,2,add(combinat:-eulerian2(n, k)*2^(2*n-k), k=0..n)), 9); # Peter Luschny, Jan 29 2016
  • Mathematica
    BellMatrix[f_Function, len_] := With[{t = Array[f, len, 0]}, Table[BellY[n, k, t], {n, 0, len - 1}, {k, 0, len - 1}]];
    rows = 12;
    M = BellMatrix[If[# == 0, 2, Sum[(#+k)!*Sum[(-1)^j/(k-j)!*Sum[(-1)^i*2^(# - i + j)*StirlingS1[# - i + j, j - i]/((# - i + j)!*i!), {i, 0, j}], {j, 1, k}], {k, 1, #}]]&, rows];
    Table[M[[n, k]], {n, 2, rows}, {k, 2, n}] // Flatten (* Jean-François Alcover, Jun 24 2018, after Peter Luschny *)
  • PARI
    T(n) = { my(g=serreverse((1 + 2*x - exp(x + O(x*x^n)))/2)); [Vecrev(p/y) | p<-Vec(serlaplace(exp(y*g)-1))] }
    { my(A=T(8)); for(i=1, #A, print(A[i])) } \\ Andrew Howroyd, Mar 28 2025

Formula

Hayes (1976, Theorem 3) gives a recurrence.

Extensions

a(46) onwards from Andrew Howroyd, Mar 28 2025

A005737 Number of fanout-free Boolean functions of n variables using And, Or and Not gates.

Original entry on oeis.org

2, 4, 14, 96, 1146, 19996, 456774, 12851768, 429005426, 16560937396, 725573492222, 35563025442192, 1927862644558314, 114519148531129036, 7397000893220477238, 516159025386346265192, 38694179227499561474786, 3101357948259644187134308
Offset: 0

Views

Author

Keywords

References

  • J. P. Hayes, Enumeration of fanout-free Boolean functions, J. ACM, 23 (1976), 700-709.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Formula

a(n) = A005736(n) + A005640(n+1). - Sean A. Irvine, Jul 21 2016
Binomial transform of A224766. - Andrew Howroyd, Mar 29 2025

Extensions

More terms from Sean A. Irvine, Jul 21 2016
Showing 1-3 of 3 results.