A025065
Number of palindromic partitions of n.
Original entry on oeis.org
1, 1, 2, 2, 4, 4, 7, 7, 12, 12, 19, 19, 30, 30, 45, 45, 67, 67, 97, 97, 139, 139, 195, 195, 272, 272, 373, 373, 508, 508, 684, 684, 915, 915, 1212, 1212, 1597, 1597, 2087, 2087, 2714, 2714, 3506, 3506, 4508, 4508, 5763, 5763, 7338, 7338, 9296, 9296, 11732, 11732, 14742, 14742, 18460, 18460, 23025, 23025, 28629, 28629
Offset: 0
The partitions for the first few values of n are as follows:
n: partitions .......................... number
1: 1 ................................... 1
2: 2 11 ................................ 2
3: 3 111 ............................... 2
4: 4 22 121 1111 ....................... 4
5: 5 131 212 11111 ..................... 4
6: 6 141 33 222 1221 11211 111111 ...... 7
7: 7 151 313 11311 232 21112 1111111 ... 7
From _Reinhard Zumkeller_, Jan 23 2010: (Start)
Partitions into 1,2,4,6,... for the first values of n:
1: 1 ....................................... 1
2: 2 11 .................................... 2
3: 21 111 .................................. 2
4: 4 22 211 1111 ........................... 4
5: 41 221 2111 11111 ....................... 4
6: 6 42 4211 222 2211 21111 111111.......... 7
7: 61 421 42111 2221 22111 211111 1111111 .. 7. (End)
The ordered version (palindromic compositions) is
A016116.
The case of palindromic prime signature is
A242414.
Palindromic partitions are ranked by
A265640, with complement
A229153.
The case of palindromic plane trees is
A319436.
The multiplicative version (palindromic factorizations) is
A344417.
A000569 counts graphical partitions.
Cf.
A000041,
A067538,
A143773,
A209816,
A338914,
A338915,
A340387,
A344296,
A344414,
A344415,
A344416.
-
a025065 = p (1:[2,4..]) where
p [] _ = 0
p _ 0 = 1
p ks'@(k:ks) m | m < k = 0
| otherwise = p ks' (m - k) + p ks m
-- Reinhard Zumkeller, Aug 12 2011
-
import Data.List (group)
a025065 = length . filter (<= 1) .
map (sum . map ((`mod` 2) . length) . group) . ps 1
where ps x 0 = [[]]
ps x y = [t:ts | t <- [x..y], ts <- ps t (y - t)]
-- Reinhard Zumkeller, Dec 18 2013
-
Map[Length[Select[IntegerPartitions[#], Count[OddQ[Transpose[Tally[#]][[2]]], True] <= 1 &]] &, Range[40]] (* Peter J. C. Moses, Jan 20 2014 *)
n = 8; Select[IntegerPartitions[n], Count[OddQ[Transpose[Tally[#]][[2]]], True] <= 1 &] (* Peter J. C. Moses, Jan 20 2014 *)
CoefficientList[Series[1/((1 - x) Product[1 - x^(2 n), {n, 1, 50}]), {x, 0, 60}], x] (* Clark Kimberling, Mar 14 2014 *)
-
N=66; q='q+O('q^N); Vec( 1/((1-q)*eta(q^2)) ) \\ Joerg Arndt, Mar 11 2014
Prepended a(0)=1, added more terms,
Joerg Arndt, Mar 11 2014
A320924
Heinz numbers of multigraphical partitions.
Original entry on oeis.org
1, 4, 9, 12, 16, 25, 27, 30, 36, 40, 48, 49, 63, 64, 70, 75, 81, 84, 90, 100, 108, 112, 120, 121, 144, 147, 154, 160, 165, 169, 175, 189, 192, 196, 198, 210, 220, 225, 243, 250, 252, 256, 264, 270, 273, 280, 286, 289, 300, 324, 325, 336, 343, 351, 352, 360
Offset: 1
The sequence of all multigraphical partitions begins: (), (11), (22), (211), (1111), (33), (222), (321), (2211), (3111), (21111), (44), (422), (111111), (431), (332), (2222), (4211), (3221), (3311), (22211), (41111), (32111), (55), (221111).
From _Gus Wiseman_, May 23 2021: (Start)
The sequence of terms together with their prime indices and a multigraph realizing each begins:
1: () | {}
4: (11) | {{1,2}}
9: (22) | {{1,2},{1,2}}
12: (112) | {{1,3},{2,3}}
16: (1111) | {{1,2},{3,4}}
25: (33) | {{1,2},{1,2},{1,2}}
27: (222) | {{1,2},{1,3},{2,3}}
30: (123) | {{1,3},{2,3},{2,3}}
36: (1122) | {{1,2},{3,4},{3,4}}
40: (1113) | {{1,4},{2,4},{3,4}}
48: (11112) | {{1,2},{3,5},{4,5}}
49: (44) | {{1,2},{1,2},{1,2},{1,2}}
63: (224) | {{1,3},{1,3},{2,3},{2,3}}
(End)
These partitions are counted by
A209816.
The case with odd weights is
A322109.
The conjugate case of equality is
A340387.
The conjugate version with odd weights allowed is
A344291.
The conjugate opposite version is
A344292.
The opposite version with odd weights allowed is
A344296.
The conjugate opposite version with odd weights allowed is
A344414.
A000070 counts non-multigraphical partitions.
A025065 counts palindromic partitions.
A035363 counts partitions into even parts.
A110618 counts partitions that are the vertex-degrees of some set multipartition with no singletons.
A334201 adds up all prime indices except the greatest.
Cf.
A000041,
A000569,
A007717,
A096373,
A265640,
A283877,
A306005,
A318361,
A320459,
A320911,
A320922,
A320923,
A320925.
-
prptns[m_]:=Union[Sort/@If[Length[m]==0,{{}},Join@@Table[Prepend[#,m[[ipr]]]&/@prptns[Delete[m,List/@ipr]],{ipr,Select[Prepend[{#},1]&/@Select[Range[2,Length[m]],m[[#]]>m[[#-1]]&],UnsameQ@@m[[#]]&]}]]];
Select[Range[1000],prptns[Flatten[MapIndexed[Table[#2,{#1}]&,If[#==1,{},Flatten[Cases[FactorInteger[#],{p_,k_}:>Table[PrimePi[p],{k}]]]]]]]!={}&]
A086543
Number of partitions of n with at least one odd part.
Original entry on oeis.org
0, 1, 1, 3, 3, 7, 8, 15, 17, 30, 35, 56, 66, 101, 120, 176, 209, 297, 355, 490, 585, 792, 946, 1255, 1498, 1958, 2335, 3010, 3583, 4565, 5428, 6842, 8118, 10143, 12013, 14883, 17592, 21637, 25525, 31185, 36711, 44583, 52382, 63261, 74173, 89134, 104303, 124754, 145698, 173525, 202268
Offset: 0
a(4)=3 because we have [3,1],[2,1,1] and [1,1,1] ([4] and [2,2] do not qualify).
These partitions have ranks
A366322.
-
g:=sum(x^(2*k-1)/product(1-x^j,j=1..2*k-1)/product(1-x^(2*j),j=k..70),k=1..70): gser:=series(g,x=0,50): seq(coeff(gser,x,n),n=0..45); # Emeric Deutsch, Mar 30 2006
-
nn=50;CoefficientList[Series[Sum[x^(2k-1)/Product[1-x^j,{j,1,2k-1}] /Product[(1-x^(2j)),{j,k,nn}],{k,1,nn}],{x,0,nn}],x] (* Geoffrey Critzer, Sep 28 2013 *)
Table[Length[Select[IntegerPartitions[n],Max[#]!=n/2&]],{n,0,30}] (* Gus Wiseman, Oct 12 2023 *)
-
x='x+O('x^66); concat([0], Vec(1/eta(x)-1/eta(x^2)) ) \\ Joerg Arndt, May 04 2013
A344296
Numbers with at least as many prime factors (counted with multiplicity) as half their sum of prime indices.
Original entry on oeis.org
1, 2, 3, 4, 6, 8, 9, 10, 12, 16, 18, 20, 24, 27, 28, 30, 32, 36, 40, 48, 54, 56, 60, 64, 72, 80, 81, 84, 88, 90, 96, 100, 108, 112, 120, 128, 144, 160, 162, 168, 176, 180, 192, 200, 208, 216, 224, 240, 243, 252, 256, 264, 270, 280, 288, 300, 320, 324, 336, 352
Offset: 1
The sequence of terms together with their prime indices begins:
1: {} 30: {1,2,3}
2: {1} 32: {1,1,1,1,1}
3: {2} 36: {1,1,2,2}
4: {1,1} 40: {1,1,1,3}
6: {1,2} 48: {1,1,1,1,2}
8: {1,1,1} 54: {1,2,2,2}
9: {2,2} 56: {1,1,1,4}
10: {1,3} 60: {1,1,2,3}
12: {1,1,2} 64: {1,1,1,1,1,1}
16: {1,1,1,1} 72: {1,1,1,2,2}
18: {1,2,2} 80: {1,1,1,1,3}
20: {1,1,3} 81: {2,2,2,2}
24: {1,1,1,2} 84: {1,1,2,4}
27: {2,2,2} 88: {1,1,1,5}
28: {1,1,4} 90: {1,2,2,3}
The case with difference at least 1 is
A322136.
A300061 lists numbers whose sum of prime indices is even.
Cf.
A001399,
A002865,
A025147,
A027336,
A036036,
A067712,
A244990,
A261144,
A325691,
A344293,
A344295.
A344415
Numbers whose greatest prime index is half their sum of prime indices.
Original entry on oeis.org
4, 9, 12, 25, 30, 40, 49, 63, 70, 84, 112, 121, 154, 165, 169, 198, 220, 264, 273, 286, 289, 325, 351, 352, 361, 364, 390, 442, 468, 520, 529, 561, 595, 624, 646, 714, 741, 748, 765, 832, 841, 850, 874, 918, 931, 952, 961, 988, 1020, 1045, 1173, 1197, 1224
Offset: 1
The sequence of terms together with their prime indices begins:
4: {1,1} 198: {1,2,2,5}
9: {2,2} 220: {1,1,3,5}
12: {1,1,2} 264: {1,1,1,2,5}
25: {3,3} 273: {2,4,6}
30: {1,2,3} 286: {1,5,6}
40: {1,1,1,3} 289: {7,7}
49: {4,4} 325: {3,3,6}
63: {2,2,4} 351: {2,2,2,6}
70: {1,3,4} 352: {1,1,1,1,1,5}
84: {1,1,2,4} 361: {8,8}
112: {1,1,1,1,4} 364: {1,1,4,6}
121: {5,5} 390: {1,2,3,6}
154: {1,4,5} 442: {1,6,7}
165: {2,3,5} 468: {1,1,2,2,6}
169: {6,6} 520: {1,1,1,3,6}
The partitions with these Heinz numbers are counted by
A035363.
A001222 counts prime factors with multiplicity.
A301987 lists numbers whose sum of prime indices equals their product.
A334201 adds up all prime indices except the greatest.
Cf.
A000070,
A001414,
A209816,
A301988,
A316413,
A316428,
A320924,
A325037,
A325038,
A325044,
A330950,
A344293,
A344294,
A344297.
-
primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[100],Max[primeMS[#]]==Total[primeMS[#]]/2&]
A344291
Numbers whose sum of prime indices is at least twice their number of prime indices (counted with multiplicity).
Original entry on oeis.org
1, 3, 5, 7, 9, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 55, 57, 58, 59, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85
Offset: 1
The sequence of terms together with their prime indices begins:
1: {} 25: {3,3} 43: {14} 62: {1,11}
3: {2} 26: {1,6} 44: {1,1,5} 63: {2,2,4}
5: {3} 27: {2,2,2} 45: {2,2,3} 65: {3,6}
7: {4} 28: {1,1,4} 46: {1,9} 66: {1,2,5}
9: {2,2} 29: {10} 47: {15} 67: {19}
10: {1,3} 30: {1,2,3} 49: {4,4} 68: {1,1,7}
11: {5} 31: {11} 50: {1,3,3} 69: {2,9}
13: {6} 33: {2,5} 51: {2,7} 70: {1,3,4}
14: {1,4} 34: {1,7} 52: {1,1,6} 71: {20}
15: {2,3} 35: {3,4} 53: {16} 73: {21}
17: {7} 37: {12} 55: {3,5} 74: {1,12}
19: {8} 38: {1,8} 57: {2,8} 75: {2,3,3}
21: {2,4} 39: {2,6} 58: {1,10} 76: {1,1,8}
22: {1,5} 41: {13} 59: {17} 77: {4,5}
23: {9} 42: {1,2,4} 61: {18} 78: {1,2,6}
For example, the prime indices of 45 are {2,2,3} with sum 7 >= 2*3, so 45 is in the sequence.
The partitions with these Heinz numbers are counted by
A110618.
The conjugate opposite version is
A344414.
The conjugate case of equality is
A344415.
A001221 counts distinct prime indices.
A001222 counts prime indices with multiplicity.
A344416
Heinz numbers of integer partitions whose sum is even and is at most twice the greatest part.
Original entry on oeis.org
3, 4, 7, 9, 10, 12, 13, 19, 21, 22, 25, 28, 29, 30, 34, 37, 39, 40, 43, 46, 49, 52, 53, 55, 57, 61, 62, 63, 66, 70, 71, 76, 79, 82, 84, 85, 87, 88, 89, 91, 94, 101, 102, 107, 111, 112, 113, 115, 116, 117, 118, 121, 129, 130, 131, 133, 134, 136, 138, 139, 146
Offset: 1
The sequence of terms together with their prime indices begins:
3: {2} 37: {12} 71: {20}
4: {1,1} 39: {2,6} 76: {1,1,8}
7: {4} 40: {1,1,1,3} 79: {22}
9: {2,2} 43: {14} 82: {1,13}
10: {1,3} 46: {1,9} 84: {1,1,2,4}
12: {1,1,2} 49: {4,4} 85: {3,7}
13: {6} 52: {1,1,6} 87: {2,10}
19: {8} 53: {16} 88: {1,1,1,5}
21: {2,4} 55: {3,5} 89: {24}
22: {1,5} 57: {2,8} 91: {4,6}
25: {3,3} 61: {18} 94: {1,15}
28: {1,1,4} 62: {1,11} 101: {26}
29: {10} 63: {2,2,4} 102: {1,2,7}
30: {1,2,3} 66: {1,2,5} 107: {28}
34: {1,7} 70: {1,3,4} 111: {2,12}
These partitions are counted by
A000070 = even-indexed terms of
A025065.
The opposite version with odd weights allowed appears to be
A322109.
The conjugate opposite version allowing odds is
A344291, counted by
A110618.
A001222 counts prime factors with multiplicity.
A265640 lists Heinz numbers of palindromic partitions.
A301987 lists numbers whose sum of prime indices equals their product.
A334201 adds up all prime indices except the greatest.
A340387 lists Heinz numbers of partitions whose sum is twice their length.
Cf.
A001414,
A074761,
A316413,
A316428,
A325037,
A325038,
A325044,
A330950,
A344293,
A344294,
A344297.
-
primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[100],EvenQ[Total[primeMS[#]]]&&Max[primeMS[#]]>=Total[primeMS[#]]/2&]
A322109
Heinz numbers of integer partitions that are the vertex-degrees of some set multipartition (multiset of nonempty sets) with no singletons.
Original entry on oeis.org
1, 4, 8, 9, 12, 16, 18, 24, 25, 27, 30, 32, 36, 40, 45, 48, 49, 50, 54, 60, 63, 64, 70, 72, 75, 80, 81, 84, 90, 96, 98, 100, 105, 108, 112, 120, 121, 125, 126, 128, 135, 140, 144, 147, 150, 154, 160, 162, 165, 168, 169, 175, 180, 189, 192, 196, 198, 200, 210
Offset: 1
Each term paired with its Heinz partition and a realizing set multipartition with no singletons:
1: (): {}
4: (11): {{1,2}}
8: (111): {{1,2,3}}
9: (22): {{1,2},{1,2}}
12: (211): {{1,2},{1,3}}
16: (1111): {{1,2,3,4}}
18: (221): {{1,2},{1,2,3}}
24: (2111): {{1,2},{1,3,4}}
25: (33): {{1,2},{1,2},{1,2}}
27: (222): {{1,2,3},{1,2,3}}
30: (321): {{1,2},{1,2},{1,3}}
32: (11111): {{1,2,3,4,5}}
36: (2211): {{1,2},{1,2,3,4}}
40: (3111): {{1,2},{1,3},{1,4}}
These partitions are counted by
A110618.
The even-weight version is
A320924.
The conjugate case of equality is
A340387.
The opposite conjugate version is
A344296.
The opposite even-weight version is
A344416.
A000070 counts non-multigraphical partitions.
A025065 counts palindromic partitions.
A035363 counts partitions into even parts.
A334201 adds up all prime indices except the greatest.
-
nrmptn[n_]:=Join@@MapIndexed[Table[#2[[1]],{#1}]&,If[n==1,{},Flatten[Cases[FactorInteger[n]//Reverse,{p_,k_}:>Table[PrimePi[p],{k}]]]]];
sqnopfacs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[sqnopfacs[n/d],Min@@#>=d&]],{d,Select[Rest[Divisors[n]],!PrimeQ[#]&&SquareFreeQ[#]&]}]]
Select[Range[100],Length[sqnopfacs[Times@@Prime/@nrmptn[#]]]>0&]
A344413
Numbers n whose sum of prime indices A056239(n) is even and is at least twice the number of prime factors A001222(n).
Original entry on oeis.org
1, 3, 7, 9, 10, 13, 19, 21, 22, 25, 27, 28, 29, 30, 34, 37, 39, 43, 46, 49, 52, 53, 55, 57, 61, 62, 63, 66, 70, 71, 75, 76, 79, 81, 82, 84, 85, 87, 88, 89, 90, 91, 94, 100, 101, 102, 107, 111, 113, 115, 116, 117, 118, 121, 129, 130, 131, 133, 134, 136, 138
Offset: 1
The sequence of terms together with their prime indices begins:
1: {} 37: {12} 75: {2,3,3}
3: {2} 39: {2,6} 76: {1,1,8}
7: {4} 43: {14} 79: {22}
9: {2,2} 46: {1,9} 81: {2,2,2,2}
10: {1,3} 49: {4,4} 82: {1,13}
13: {6} 52: {1,1,6} 84: {1,1,2,4}
19: {8} 53: {16} 85: {3,7}
21: {2,4} 55: {3,5} 87: {2,10}
22: {1,5} 57: {2,8} 88: {1,1,1,5}
25: {3,3} 61: {18} 89: {24}
27: {2,2,2} 62: {1,11} 90: {1,2,2,3}
28: {1,1,4} 63: {2,2,4} 91: {4,6}
29: {10} 66: {1,2,5} 94: {1,15}
30: {1,2,3} 70: {1,3,4} 100: {1,1,3,3}
34: {1,7} 71: {20} 101: {26}
For example, 75 has 3 prime indices {2,3,3} with sum 8 >= 2*3, so 75 is in the sequence.
These are the Heinz numbers of partitions counted by
A209816 and
A110618.
A subset of
A300061 (sum of prime indices is even).
The conjugate version appears to be
A320924 (allowing odd weights:
A322109).
Allowing odd weights gives
A344291.
The opposite version allowing odd weights is
A344296.
The conjugate opposite version allowing odd weights is
A344414.
The case of equality in the conjugate case is
A344415.
A001222 counts prime factors with multiplicity.
A301987 lists numbers whose sum of prime indices equals their product.
A330950 counts partitions of n with Heinz number divisible by n.
A334201 adds up all prime indices except the greatest.
Cf.
A001414,
A025065,
A067538,
A301988,
A316413,
A316428,
A325037,
A325038,
A325044,
A338914,
A344294,
A344297.
-
filter:= proc(n) local F,a,t;
F:= ifactors(n)[2];
a:= add((numtheory:-pi(t[1])-2)*t[2],t=F);
a::even and a >= 0
end proc:
select(filter, [$1..300]); # Robert Israel, Oct 10 2024
-
primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[100],EvenQ[Total[primeMS[#]]]&&PrimeOmega[#]<=Total[primeMS[#]]/2&]
A366319
Numbers k such that the sum of prime indices of k is not twice the maximum prime index of k, meaning A056239(k) != 2 * A061395(k).
Original entry on oeis.org
1, 2, 3, 5, 6, 7, 8, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 71, 72, 73, 74, 75, 76
Offset: 1
The prime indices of 90 are {1,2,2,3}, with sum 8 and twice maximum 6, so 90 is in the sequence.
Partitions of this type are counted by
A086543.
For length instead of maximum we have the complement of
A340387.
A334201 adds up all prime indices except the greatest.
-
prix[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[100],Max[prix[#]]!=Total[prix[#]]/2&]
Showing 1-10 of 14 results.
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