A237984
Number of partitions of n whose mean is a part.
Original entry on oeis.org
1, 2, 2, 3, 2, 5, 2, 6, 5, 8, 2, 21, 2, 14, 22, 30, 2, 61, 2, 86, 67, 45, 2, 283, 66, 80, 197, 340, 2, 766, 2, 663, 543, 234, 703, 2532, 2, 388, 1395, 4029, 2, 4688, 2, 4476, 7032, 1005, 2, 17883, 2434, 9713, 7684, 14472, 2, 25348, 17562, 37829, 16786, 3721
Offset: 1
a(6) counts these partitions: 6, 33, 321, 222, 111111.
From _Gus Wiseman_, Sep 14 2019: (Start)
The a(1) = 1 through a(10) = 8 partitions (A = 10):
1 2 3 4 5 6 7 8 9 A
11 111 22 11111 33 1111111 44 333 55
1111 222 2222 432 22222
321 3221 531 32221
111111 4211 111111111 33211
11111111 42211
52111
1111111111
(End)
The Heinz numbers of these partitions are
A327473.
A similar sequence for subsets is
A065795.
Partitions without their mean are
A327472.
-
Table[Count[IntegerPartitions[n], p_ /; MemberQ[p, Mean[p]]], {n, 40}]
-
from sympy.utilities.iterables import partitions
def A237984(n): return sum(1 for s,p in partitions(n,size=True) if not n%s and n//s in p) # Chai Wah Wu, Sep 21 2023
A290689
Number of transitive rooted trees with n nodes.
Original entry on oeis.org
1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 88, 143, 229, 370, 592, 955, 1527, 2457, 3929, 6304, 10081
Offset: 1
The a(7) = 8 7-node transitive rooted trees are: (o(oooo)), (oo(ooo)), (o(o)((o))), (o(o)(oo)), (ooo(oo)), (oo(o)(o)), (oooo(o)), (oooooo).
-
nn=18;
rtall[n_]:=If[n===1,{{}},Module[{cas},Union[Sort/@Join@@(Tuples[rtall/@#]&/@IntegerPartitions[n-1])]]];
Table[Length[Select[rtall[n],Complement[Union@@#,#]==={}&]],{n,nn}]
A065795
Number of subsets of {1,2,...,n} that contain the average of their elements.
Original entry on oeis.org
1, 2, 4, 6, 10, 16, 26, 42, 72, 124, 218, 390, 706, 1292, 2388, 4436, 8292, 15578, 29376, 55592, 105532, 200858, 383220, 732756, 1403848, 2694404, 5179938, 9973430, 19229826, 37125562, 71762396, 138871260, 269021848, 521666984, 1012520400, 1966957692, 3824240848
Offset: 1
a(4)=6, since {1}, {2}, {3}, {4}, {1,2,3} and {2,3,4} contain their averages.
From _Gus Wiseman_, Sep 14 2019: (Start)
The a(1) = 1 through a(6) = 16 subsets:
{1} {1} {1} {1} {1} {1}
{2} {2} {2} {2} {2}
{3} {3} {3} {3}
{1,2,3} {4} {4} {4}
{1,2,3} {5} {5}
{2,3,4} {1,2,3} {6}
{1,3,5} {1,2,3}
{2,3,4} {1,3,5}
{3,4,5} {2,3,4}
{1,2,3,4,5} {2,4,6}
{3,4,5}
{4,5,6}
{1,2,3,6}
{1,4,5,6}
{1,2,3,4,5}
{2,3,4,5,6}
(End)
Subsets containing n whose mean is an element are
A000016.
The version for integer partitions is
A237984.
Subsets not containing their mean are
A327471.
-
Table[ Sum[a = Select[Divisors[i], OddQ[ # ] &]; Apply[ Plus, 2^(i/a) * EulerPhi[a]]/i, {i, n}]/2, {n, 34}]
(* second program *)
Table[Length[Select[Subsets[Range[n]],MemberQ[#,Mean[#]]&]],{n,0,10}] (* Gus Wiseman, Sep 14 2019 *)
-
a(n) = (1/2)*sum(i=1, n, (1/i)*sumdiv(i, d, if (d%2, 2^(i/d)*eulerphi(d)))); \\ Michel Marcus, Dec 20 2020
-
from sympy import totient, divisors
def A065795(n): return sum((sum(totient(d)<>(~k&k-1).bit_length(),generator=True))<<1)//k for k in range(1,n+1))>>1 # Chai Wah Wu, Feb 22 2023
A353390
Number of compositions of n whose own run-lengths are a subsequence (not necessarily consecutive).
Original entry on oeis.org
1, 1, 0, 0, 1, 2, 3, 2, 2, 8, 17, 26, 43, 77, 129, 210, 351, 569
Offset: 0
The a(0) = 1 through a(9) = 8 compositions (empty columns indicated by dots):
() (1) . . (22) (122) (1122) (11221) (21122) (333)
(221) (1221) (12211) (22112) (22113)
(2211) (22122)
(31122)
(121122)
(122112)
(211221)
(221121)
For example, the composition y = (2,2,3,3,1) has run-lengths (2,2,1), which form a (non-consecutive) subsequence, so y is counted under a(11).
The version for partitions is
A325702.
These compositions are ranked by
A353402.
The recursive consecutive version is
A353430.
A325705 counts partitions containing all of their distinct multiplicities.
A329739 counts compositions with all distinct run-lengths, for runs
A351013.
A353400 counts compositions with all run-lengths > 2.
Cf.
A005811,
A103295,
A114901,
A181591,
A238279,
A242882,
A324572,
A333755,
A351017,
A353401,
A353426.
-
Table[Length[Select[Join@@Permutations/@IntegerPartitions[n], MemberQ[Subsets[#],Length/@Split[#]]&]],{n,0,15}]
A353391
Number of compositions of n that are empty, a singleton, or whose run-lengths are a subsequence that is already counted.
Original entry on oeis.org
1, 1, 1, 1, 2, 1, 3, 1, 1, 4, 5, 7, 9, 11, 15, 22, 38, 45, 87, 93
Offset: 0
The a(9) = 4 through a(14) = 15 compositions (A..E = 10..14):
(9) (A) (B) (C) (D) (E)
(333) (2233) (141122) (2244) (161122) (2255)
(121122) (3322) (221123) (4422) (221125) (5522)
(221121) (131122) (221132) (151122) (221134) (171122)
(221131) (221141) (221124) (221143) (221126)
(231122) (221142) (221152) (221135)
(321122) (221151) (221161) (221153)
(241122) (251122) (221162)
(421122) (341122) (221171)
(431122) (261122)
(521122) (351122)
(531122)
(621122)
(122121122)
(221121221)
The non-recursive reverse version is
A353403.
The consecutive version is
A353430.
These compositions are ranked by
A353431.
A114901 counts compositions with no runs of length 1.
A325705 counts partitions containing all of their distinct multiplicities.
A329739 counts compositions with all distinct run-length.
Cf.
A005811,
A032020,
A103295,
A114640,
A165413,
A181591,
A242882,
A324572,
A325702,
A333755,
A351013,
A353401.
-
yosQ[y_]:=Length[y]<=1||MemberQ[Subsets[y],Length/@Split[y]]&&yosQ[Length/@Split[y]];
Table[Length[Select[Join@@Permutations/@IntegerPartitions[n],yosQ]],{n,0,15}]
A353402
Numbers k such that the k-th composition in standard order has its own run-lengths as a subsequence (not necessarily consecutive).
Original entry on oeis.org
0, 1, 10, 21, 26, 43, 53, 58, 107, 117, 174, 186, 292, 314, 346, 348, 349, 373, 430, 442, 570, 585, 586, 629, 676, 693, 696, 697, 698, 699, 804, 826, 858, 860, 861, 885, 954, 1082, 1141, 1173, 1210, 1338, 1353, 1387, 1392, 1393, 1394, 1396, 1397, 1398, 1466
Offset: 0
The initial terms, their binary expansions, and the corresponding standard compositions:
0: 0 ()
1: 1 (1)
10: 1010 (2,2)
21: 10101 (2,2,1)
26: 11010 (1,2,2)
43: 101011 (2,2,1,1)
53: 110101 (1,2,2,1)
58: 111010 (1,1,2,2)
107: 1101011 (1,2,2,1,1)
117: 1110101 (1,1,2,2,1)
174: 10101110 (2,2,1,1,2)
186: 10111010 (2,1,1,2,2)
292: 100100100 (3,3,3)
314: 100111010 (3,1,1,2,2)
346: 101011010 (2,2,1,2,2)
348: 101011100 (2,2,1,1,3)
349: 101011101 (2,2,1,1,2,1)
373: 101110101 (2,1,1,2,2,1)
430: 110101110 (1,2,2,1,1,2)
442: 110111010 (1,2,1,1,2,2)
These compositions are counted by
A353390.
A005811 counts runs in binary expansion.
A333769 lists run-lengths of compositions in standard order.
Statistics of standard compositions:
Classes of standard compositions:
Cf.
A114640,
A165413,
A181819,
A318928,
A325705,
A329738,
A333224/
A333257,
A333755,
A353393,
A353403,
A353430.
-
stc[n_]:=Differences[Prepend[Join@@Position[ Reverse[IntegerDigits[n,2]],1],0]]//Reverse;
rosQ[y_]:=Length[y]==0||MemberQ[Subsets[y],Length/@Split[y]];
Select[Range[0,100],rosQ[stc[#]]&]
A353392
Number of compositions of n whose own run-lengths are a consecutive subsequence.
Original entry on oeis.org
1, 1, 0, 0, 1, 2, 2, 2, 2, 8, 12, 16, 20, 35, 46, 59, 81, 109, 144, 202, 282
Offset: 0
The a(0) = 0 through a(10) = 12 compositions (empty columns indicated by dots, 0 is the empty composition):
0 1 . . 22 122 1122 11221 21122 333 1333
221 2211 12211 22112 22113 2233
22122 3322
31122 3331
121122 22114
122112 41122
211221 122113
221121 131122
221131
311221
1211221
1221121
The non-consecutive version for partitions is
A325702.
The non-consecutive reverse version is
A353403.
These compositions are ranked by
A353432.
A329739 counts compositions with all distinct run-lengths.
Cf.
A008965,
A032020,
A103295,
A103300,
A114901,
A238279,
A324572,
A325705,
A333224,
A333755,
A351013,
A353401.
-
Table[Length[Select[Join@@Permutations/@IntegerPartitions[n],#=={}||MemberQ[Join@@Table[Take[#,{i,j}],{i,Length[#]},{j,i,Length[#]}],Length/@Split[#]]&]],{n,0,15}]
A353403
Number of compositions of n whose own reversed run-lengths are a subsequence (not necessarily consecutive).
Original entry on oeis.org
1, 1, 0, 0, 3, 2, 5, 12, 16, 30, 45, 94, 159, 285, 477, 864, 1487, 2643
Offset: 0
The a(0) = 1 through a(7) = 12 compositions:
() (1) . . (22) (1121) (1113) (1123)
(112) (1211) (1122) (1132)
(211) (1221) (2311)
(2211) (3211)
(3111) (11131)
(11212)
(11221)
(12112)
(12211)
(13111)
(21121)
(21211)
The non-reversed recursive consecutive version is
A353430.
A325705 counts partitions containing all of their distinct multiplicities.
A329739 counts compositions with all distinct run-lengths, for runs
A351013.
-
Table[Length[Select[Join@@Permutations/@ IntegerPartitions[n],MemberQ[Subsets[#],Reverse[Length/@Split[#]]]&]],{n,0,15}]
A353431
Numbers k such that the k-th composition in standard order is empty, a singleton, or has its own run-lengths as a subsequence (not necessarily consecutive) that is already counted.
Original entry on oeis.org
0, 1, 2, 4, 8, 10, 16, 32, 43, 58, 64, 128, 256, 292, 349, 442, 512, 586, 676, 697, 826, 1024, 1210, 1338, 1393, 1394, 1396, 1594, 2048, 2186, 2234, 2618, 2696, 2785, 2786, 2792, 3130, 4096, 4282, 4410, 4666, 5178, 5569, 5570, 5572, 5576, 5584, 6202, 8192
Offset: 1
The initial terms, their binary expansions, and the corresponding standard compositions:
0: 0 ()
1: 1 (1)
2: 10 (2)
4: 100 (3)
8: 1000 (4)
10: 1010 (2,2)
16: 10000 (5)
32: 100000 (6)
43: 101011 (2,2,1,1)
58: 111010 (1,1,2,2)
64: 1000000 (7)
128: 10000000 (8)
256: 100000000 (9)
292: 100100100 (3,3,3)
349: 101011101 (2,2,1,1,2,1)
442: 110111010 (1,2,1,1,2,2)
512: 1000000000 (10)
586: 1001001010 (3,3,2,2)
676: 1010100100 (2,2,3,3)
697: 1010111001 (2,2,1,1,3,1)
The non-recursive version for partitions is
A325755, counted by
A325702.
These compositions are counted by
A353391.
A005811 counts runs in binary expansion.
Statistics of standard compositions:
Classes of standard compositions:
Cf.
A032020,
A044813,
A114640,
A165413,
A181819,
A329739,
A318928,
A325705,
A333224,
A353427,
A353403.
-
stc[n_]:=Differences[Prepend[Join@@ Position[Reverse[IntegerDigits[n,2]],1],0]]//Reverse;
rorQ[y_]:=Length[y]<=1||MemberQ[Subsets[y],Length/@Split[y]]&& rorQ[Length/@Split[y]];
Select[Range[0,100],rorQ[stc[#]]&]
A353432
Numbers k such that the k-th composition in standard order has its own run-lengths as a consecutive subsequence.
Original entry on oeis.org
0, 1, 10, 21, 26, 43, 58, 107, 117, 174, 186, 292, 314, 346, 348, 349, 373, 430, 442, 570, 585, 586, 629, 676, 696, 697, 804, 826, 860, 861, 885, 1082, 1141, 1173, 1210, 1338, 1387, 1392, 1393, 1394, 1396, 1594, 1653, 1700, 1720, 1721, 1882, 2106, 2165, 2186
Offset: 1
The initial terms, their binary expansions, and the corresponding standard compositions:
0: 0 ()
1: 1 (1)
10: 1010 (2,2)
21: 10101 (2,2,1)
26: 11010 (1,2,2)
43: 101011 (2,2,1,1)
58: 111010 (1,1,2,2)
107: 1101011 (1,2,2,1,1)
117: 1110101 (1,1,2,2,1)
174: 10101110 (2,2,1,1,2)
186: 10111010 (2,1,1,2,2)
292: 100100100 (3,3,3)
314: 100111010 (3,1,1,2,2)
346: 101011010 (2,2,1,2,2)
348: 101011100 (2,2,1,1,3)
349: 101011101 (2,2,1,1,2,1)
373: 101110101 (2,1,1,2,2,1)
430: 110101110 (1,2,2,1,1,2)
442: 110111010 (1,2,1,1,2,2)
These compositions are counted by
A353392.
A005811 counts runs in binary expansion.
Statistics of standard compositions:
Classes of standard compositions:
Cf.
A044813,
A165413,
A181819,
A318928,
A325702,
A325705,
A325755,
A333224,
A333755,
A353389,
A353393,
A353403.
-
stc[n_]:=Differences[Prepend[Join@@ Position[Reverse[IntegerDigits[n,2]],1],0]]//Reverse;
rorQ[y_]:=Length[y]==0||MemberQ[Join@@Table[Take[y,{i,j}],{i,Length[y]},{j,i,Length[y]}],Length/@Split[y]];
Select[Range[0,10000],rorQ[stc[#]]&]
Showing 1-10 of 14 results.
Comments