A344181 -id:A344181 - cp's OEIS frontend

A344179 Jordan-Polya numbers (A001013) not in A344181.

72, 216, 432, 1296, 1728, 2592, 5184, 7776, 10368, 14400, 15552, 28800, 31104, 41472, 46656, 51840, 57600, 62208, 93312, 115200, 120960, 124416, 155520, 186624, 230400, 248832, 279936, 311040, 373248, 460800, 559872, 604800, 746496, 921600, 933120, 995328, 1088640, 1119744, 1209600, 1244160, 1492992, 1679616, 1728000

Offset: 1

Antti Karttunen, May 18 2021

nonn

These are numbers that are products of factorial numbers (A000142), but whose presence in A001013 cannot be determined by a simple greedy algorithm that repeatedly divides the largest factorial divisor [= A055874(n)!] off, until only 1 remains.

			72 = 2*6*6 = 2! * 3! * 3! is present in A001013, and as it is not present in A344181 (because when it is divided by its largest factorial divisor 24, we get 72/24 = 3, an odd number that is not a factorial itself), it is therefore present in this sequence.

David A. Corneth, Table of n, a(n) for n = 1..10000
Index entries for sequences related to factorial numbers

Setwise difference of A001013 and A344181.

Cf. A000142, A055874, A076934, A093411.

fct = Array[#! &, 10]; prev = {}; jp = fct; While[jp != prev, prev = jp; jp = Select[Union @@ Outer[Times, jp, fct], # <= fct[[-1]] &]]; fctdiv[n_] := Module[{m = 1, k = 1}, While[Divisible[n, m], k++; m *= k]; m /= k; n/m]; Select[jp, FixedPoint[fctdiv, #] != 1 &] (* Amiram Eldar, May 22 2021 *)

search_up_to = 2^22;
A076934(n) = for(k=2, oo , if(n%k, return(n), n /= k));
A093411(n) = if(!n,n, if(n%2, n, A093411(A076934(n))));
A001013list(lim, mx=lim)=if(lim<2, return([1])); my(v=[1], t=1); for(n=2, mx, t*=n; if(t>lim, break); v=concat(v, t*A001013list(lim\t, t))); Set(v) \\ From A001013
v001013 = A001013list(search_up_to);
A001013(n) = v001013[n];
isA344179(n) = if(v001013[#v001013]A093411(n))&&vecsearch(v001013,n)));
for(n=1,search_up_to,if(isA344179(n),print1(n,", ")));

A001013 Jordan-Polya numbers: products of factorial numbers A000142.

Original entry on oeis.org

1, 2, 4, 6, 8, 12, 16, 24, 32, 36, 48, 64, 72, 96, 120, 128, 144, 192, 216, 240, 256, 288, 384, 432, 480, 512, 576, 720, 768, 864, 960, 1024, 1152, 1296, 1440, 1536, 1728, 1920, 2048, 2304, 2592, 2880, 3072, 3456, 3840, 4096, 4320, 4608, 5040, 5184, 5760

Offset: 1

N. J. A. Sloane

Also, numbers of the form 1^d_1*2^d_2*3^d_3*...*k^d_k where k, d_1, ..., d_k are natural numbers satisfying d_1 >= d_2 >= d_3 >= ... >= d_k >= 1. - N. J. A. Sloane, Jun 14 2015
Possible orders of automorphism groups of trees.
Except for the numbers 2, 9 and 10 this sequence is conjectured to be the same as A034878.
Equivalently, (a(n)/6)*(6*x^2 - 6*x + (6*x-3)*a(n) + 2*a(n)^2 + 1) = N^2 has an integer solution. - Ralf Stephan, Dec 04 2004
Named after the French mathematician Camille Jordan (1838-1922) and the Hungarian mathematician George Pólya (1887-1985). - Amiram Eldar, May 22 2021
Possible numbers of transitive orientations of comparability graphs (Golumbic, 1977). - David Eppstein, Dec 29 2021

			864 = (3!)^2*4!.

Richard K. Guy, Unsolved Problems in Number Theory, 3rd Edition, Springer, 2004, Section B23, p. 123.
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).

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 (first 987 terms from T. D. Noe)
Jean-Marie De Koninck, Nicolas Doyon, A. Arthur Bonkli Razafindrasoanaivolala and William Verreault, Bounds for the counting function of the Jordan-Pólya numbers, Archivum Mathematicum, Vol. 56, No. 3 (2020), pp. 141-152; also on arXiv, arXiv:2107.09114 [math.NT], 2021.
Martin Charles Golumbic, Comparability graphs and a new matroid, Journal of Combinatorial Theory, Series B, Vol. 22, No. 1 (1977), pp. 68-90.
Camille Jordan, Sur les assemblages de lignes, Journal für die reine und angewandte Mathematik, Vol. 70 (1869), pp. 185-190; alternative link.
Robert A. Melter, Autometrized unary algebras, J. Combinatorial Theory, Vol. 5, No. 1 (1968), pp. 21-29.
George Pólya, Kombinatorische Anzahlbestimmungen für Gruppen, Graphen und chemische Verbindungen, Acta Mathematica, Vol. 68 (1937), pp. 145-254; alternative link.
Eric Weisstein's World of Mathematics, Factorial Products.
Index entries for sequences related to factorial numbers
Index entries for sequences related to trees

Cf. A000142, A034878, A093373 (complement), A344438 (characteristic function).
Union of A344181 and A344179. Subsequence of A025487 (see also A064783).
See also A359636 and A359751.

import Data.Set (empty, fromList, deleteFindMin, union)
import qualified Data.Set as Set (null)
a001013 n = a001013_list !! (n-1)
a001013_list = 1 : h 0 empty [1] (drop 2 a000142_list) where
   h z s mcs xs'@(x:xs)
    | Set.null s || x < m = h z (union s (fromList $ map (* x) mcs)) mcs xs
    | m == z = h m s' mcs xs'
    | otherwise = m : h m (union s' (fromList (map (* m) $ init (m:mcs)))) (m:mcs) xs'
    where (m, s') = deleteFindMin s
-- Reinhard Zumkeller, Nov 13 2014

N:= 10000: # get all terms <= N
S:= {1}:
for k from 2 do
  kf:= k!;
  if kf > N then break fi;
  S := S union {seq(seq(kf^j * s, j = 1 .. floor(log[kf](N/s))),s=S)};
od:
S;   # if using Maple 11 or earlier, uncomment the next line:
# sort(convert(S,list));
# Robert Israel, Sep 09 2014

For[p=0; a=f=Table[n!, {n, 1, 8}], p=!=a, p=a; a=Select[Union@@Outer[Times, f, a], #<=8!&]]; a

list(lim,mx=lim)=if(lim<2, return([1])); my(v=[1],t=1); for(n=2,mx, t*=n; if(t>lim, break); v=concat(v,t*list(lim\t, t))); Set(v) \\ Charles R Greathouse IV, May 18 2015

def aupto(lim, mx=None):
    if lim < 2: return [1]
    v, t = [1], 1
    if mx == None: mx = lim
    for k in range(2, mx+1):
        t *= k
        if t > lim: break
        v += [t*rest for rest in aupto(lim//t, t)]
    return sorted(set(v))
print(aupto(5760)) # Michael S. Branicky, Jul 21 2021 after Charles R Greathouse IV

# uses[prod_hull from A246663]
prod_hull(factorial, 5760) # Peter Luschny, Sep 09 2014

More terms, formula from Christian G. Bower, Dec 15 1999

Edited by Dean Hickerson, Sep 17 2002

A093411 Divide n by the largest factorial that divides it and repeat until an odd number is reached, which will be the result; a(0) = 0.

Original entry on oeis.org

0, 1, 1, 3, 1, 5, 1, 7, 1, 9, 5, 11, 1, 13, 7, 15, 1, 17, 3, 19, 5, 21, 11, 23, 1, 25, 13, 27, 7, 29, 5, 31, 1, 33, 17, 35, 1, 37, 19, 39, 5, 41, 7, 43, 11, 45, 23, 47, 1, 49, 25, 51, 13, 53, 9, 55, 7, 57, 29, 59, 5, 61, 31, 63, 1, 65, 11, 67, 17, 69, 35, 71, 3, 73, 37, 75, 19, 77, 13, 79

Offset: 0

Amarnath Murthy, Mar 30 2004

a(n) is odd for all positive n>0; a(n) = n iff n is odd.

			a(18) = 3, 18/6 = 3. though 18/2 = 9.

Antti Karttunen, Table of n, a(n) for n = 0..40319
Index entries for sequences related to factorial numbers

For bisection see A109375, for positions of ones, A344181.
Cf. A000142, A076934, A329379.
Cf. also A328478.

f[n_] := Block[{m = n, k = n}, While[k > 1, While[ IntegerQ[m/k! ], m = m/k! ]; k-- ]; m]; Table[ f[n], {n, 0, 79}] (* Robert G. Wilson v *)

A076934(n) = for(k=2, oo , if(n%k, return(n), n /= k));
A093411(n) = if(!n,n, if(n%2, n, A093411(A076934(n)))); \\ Antti Karttunen, May 18 2021

From Antti Karttunen, May 18 2021: (Start)
a(0) = 0, a(2n+1) = 2n+1, a(2n) = a(A076934(2n)).
a(n) = n / A329379(n).
(End)

Edited, corrected and extended by Robert G. Wilson v, Aug 25 2005

Definition further clarified by Antti Karttunen, May 18 2021

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A344179 Jordan-Polya numbers (A001013) not in A344181.

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A001013 Jordan-Polya numbers: products of factorial numbers A000142.

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A093411 Divide n by the largest factorial that divides it and repeat until an odd number is reached, which will be the result; a(0) = 0.

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