A288728
Number of sum-free sets that can be created by adding n to all sum-free sets [1..n-1].
Original entry on oeis.org
1, 1, 3, 3, 7, 8, 18, 19, 47, 43, 102, 116, 238, 240, 553, 554, 1185, 1259, 2578, 2607, 5873, 5526, 11834, 12601, 24692, 24390, 53735, 52534, 107445, 107330, 218727, 215607, 461367, 427778, 891039, 910294, 1804606, 1706828, 3695418, 3411513, 7136850, 6892950
Offset: 1
1 can be added to {};
2 can be added to {} but not {1};
3 can be added to {},{1},{2};
4 can be added to {},{1},{3} but not {2},{1,3},{2,3}.
From _Gus Wiseman_, Aug 12 2023: (Start)
The a(1) = 1 through a(7) = 18 sum-free sets with maximum n:
{1} {2} {3} {4} {5} {6} {7}
{1,3} {1,4} {1,5} {1,6} {1,7}
{2,3} {3,4} {2,5} {2,6} {2,7}
{3,5} {4,6} {3,7}
{4,5} {5,6} {4,7}
{1,3,5} {1,4,6} {5,7}
{3,4,5} {2,5,6} {6,7}
{4,5,6} {1,3,7}
{1,4,7}
{1,5,7}
{2,3,7}
{2,6,7}
{3,5,7}
{4,5,7}
{4,6,7}
{5,6,7}
{1,3,5,7}
{4,5,6,7}
(End)
For non-binary sum-free subsets of {1..n} we have
A237667.
For sum-free partitions we have
A364345, without re-using parts
A236912.
The complement without re-using parts is
A364756, differences of
A088809.
-
Table[Length[Select[Subsets[Range[n]],MemberQ[#,n]&&Intersection[#,Total/@Tuples[#,2]]=={}&]],{n,10}] (* Gus Wiseman, Aug 12 2023 *)
A363226
Number of strict integer partitions of n containing some three possibly equal parts (a,b,c) such that a + b = c. A variation of sum-full strict partitions.
Original entry on oeis.org
0, 0, 0, 1, 0, 0, 2, 1, 2, 3, 5, 4, 6, 7, 11, 11, 16, 18, 26, 29, 34, 42, 51, 62, 72, 84, 101, 119, 142, 166, 191, 226, 262, 300, 354, 405, 467, 540, 623, 705, 807, 927, 1060, 1206, 1369, 1551, 1760, 1998, 2248, 2556, 2861, 3236, 3628, 4100, 4587, 5152, 5756
Offset: 0
The a(3) = 1 through a(15) = 11 partitions (A=10, B=11, C=12):
21 . . 42 421 431 63 532 542 84 643 653 A5
321 521 432 541 632 642 742 743 843
621 631 821 651 841 752 942
721 5321 921 A21 761 C21
4321 5421 5431 842 6432
6321 6421 B21 6531
7321 5432 7431
6431 7521
6521 8421
7421 9321
8321 54321
For subsets of {1..n} we have
A093971 (sum-full sets), complement
A007865.
A236912 counts sum-free partitions not re-using parts, complement
A237113.
-
Table[Length[Select[IntegerPartitions[n],UnsameQ@@#&&Select[Tuples[#,3],#[[1]]+#[[2]]==#[[3]]&]!={}&]],{n,0,30}]
-
from itertools import combinations_with_replacement
from collections import Counter
from sympy.utilities.iterables import partitions
def A363226(n): return sum(1 for p in partitions(n) if max(p.values(),default=0)==1 and any(q[0]+q[1]==q[2] for q in combinations_with_replacement(sorted(Counter(p).elements()),3))) # Chai Wah Wu, Sep 20 2023
A367226
Numbers m whose prime indices have a nonnegative linear combination equal to bigomega(m).
Original entry on oeis.org
1, 2, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 26, 28, 30, 32, 33, 34, 36, 38, 39, 40, 42, 44, 45, 46, 48, 50, 51, 52, 54, 56, 57, 58, 60, 62, 64, 66, 68, 69, 70, 72, 74, 75, 76, 78, 80, 81, 82, 84, 86, 87, 88, 90, 92, 93, 94, 96, 98, 100, 102, 104
Offset: 1
The prime indices of 24 are {1,1,1,2} with (1+1+1+1) = 4 or (1+1)+(2) = 4 or (2+2) = 4, so 24 is in the sequence.
The terms together with their prime indices begin:
1: {}
2: {1}
4: {1,1}
6: {1,2}
8: {1,1,1}
9: {2,2}
10: {1,3}
12: {1,1,2}
14: {1,4}
15: {2,3}
16: {1,1,1,1}
18: {1,2,2}
20: {1,1,3}
21: {2,4}
22: {1,5}
24: {1,1,1,2}
26: {1,6}
28: {1,1,4}
30: {1,2,3}
32: {1,1,1,1,1}
The following sequences count and rank integer partitions and finite sets according to whether their length is a subset-sum or linear combination of the parts. The current sequence is starred.
sum-full sum-free comb-full comb-free
-------------------------------------------
A046663 counts partitions of n without a subset-sum k, strict
A365663.
-
prix[n_]:=If[n==1,{}, Flatten[Cases[FactorInteger[n], {p_,k_}:>Table[PrimePi[p],{k}]]]];
combs[n_,y_]:=With[{s=Table[{k,i},{k,y}, {i,0,Floor[n/k]}]}, Select[Tuples[s], Total[Times@@@#]==n&]];
Select[Range[100], combs[PrimeOmega[#], Union[prix[#]]]!={}&]
A367227
Numbers m whose prime indices have no nonnegative linear combination equal to bigomega(m).
Original entry on oeis.org
3, 5, 7, 11, 13, 17, 19, 23, 25, 27, 29, 31, 35, 37, 41, 43, 47, 49, 53, 55, 59, 61, 63, 65, 67, 71, 73, 77, 79, 83, 85, 89, 91, 95, 97, 99, 101, 103, 107, 109, 113, 115, 117, 119, 121, 127, 131, 133, 137, 139, 143, 145, 147, 149, 151, 153, 155, 157, 161, 163
Offset: 1
The prime indices of 24 are {1,1,1,2} with (1+1+1+1) = 4 or (1+1)+(2) = 4 or (2+2) = 4, so 24 is not in the sequence.
The terms together with their prime indices begin:
3: {2} 43: {14} 85: {3,7}
5: {3} 47: {15} 89: {24}
7: {4} 49: {4,4} 91: {4,6}
11: {5} 53: {16} 95: {3,8}
13: {6} 55: {3,5} 97: {25}
17: {7} 59: {17} 99: {2,2,5}
19: {8} 61: {18} 101: {26}
23: {9} 63: {2,2,4} 103: {27}
25: {3,3} 65: {3,6} 107: {28}
27: {2,2,2} 67: {19} 109: {29}
29: {10} 71: {20} 113: {30}
31: {11} 73: {21} 115: {3,9}
35: {3,4} 77: {4,5} 117: {2,2,6}
37: {12} 79: {22} 119: {4,7}
41: {13} 83: {23} 121: {5,5}
The following sequences count and rank integer partitions and finite sets according to whether their length is a subset-sum or linear combination of the parts. The current sequence is starred.
sum-full sum-free comb-full comb-free
-------------------------------------------
A124506 appears to count combination-free subsets, differences of
A326083.
Cf.
A000720,
A046663,
A088314,
A106529,
A116861,
A236912,
A364345,
A364346,
A364347,
A364350,
A365073,
A365312.
-
prix[n_]:=If[n==1,{}, Flatten[Cases[FactorInteger[n], {p_,k_}:>Table[PrimePi[p], {k}]]]];
combs[n_,y_]:=With[{s=Table[{k,i}, {k,y}, {i,0,Floor[n/k]}]}, Select[Tuples[s], Total[Times@@@#]==n&]];
Select[Range[100], combs[PrimeOmega[#], Union[prix[#]]]=={}&]
A383512
Heinz numbers of conjugate Wilf partitions.
Original entry on oeis.org
1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 20, 22, 23, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 55, 56, 57, 58, 59, 61, 62, 64, 67, 68, 69, 71, 73, 74, 75, 76, 77, 79, 80, 81, 82, 83, 85
Offset: 1
The terms together with their prime indices begin:
1: {} 17: {7} 35: {3,4}
2: {1} 19: {8} 37: {12}
3: {2} 20: {1,1,3} 38: {1,8}
4: {1,1} 22: {1,5} 39: {2,6}
5: {3} 23: {9} 40: {1,1,1,3}
7: {4} 25: {3,3} 41: {13}
8: {1,1,1} 26: {1,6} 43: {14}
9: {2,2} 27: {2,2,2} 44: {1,1,5}
10: {1,3} 28: {1,1,4} 45: {2,2,3}
11: {5} 29: {10} 46: {1,9}
13: {6} 31: {11} 47: {15}
14: {1,4} 32: {1,1,1,1,1} 49: {4,4}
15: {2,3} 33: {2,5} 50: {1,3,3}
16: {1,1,1,1} 34: {1,7} 51: {2,7}
Partitions of this type are counted by
A098859.
Also requiring distinct multiplicities gives
A383532, counted by
A383507.
These are the positions of strict rows in
A383534, or squarefree numbers in
A383535.
A122111 represents conjugation in terms of Heinz numbers.
A325349 counts partitions with distinct augmented differences, ranks
A325366.
A383530 counts partitions that are not Wilf or conjugate Wilf, ranks
A383531.
A383709 counts Wilf partitions with distinct augmented differences, ranks
A383712.
-
prix[n_]:=If[n==1,{}, Flatten[Cases[FactorInteger[n], {p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[100], UnsameQ@@DeleteCases[Differences[Prepend[prix[#],0]],0]&]
A363260
Number of integer partitions of n with parts disjoint from first differences of parts, meaning no part is the difference of two consecutive parts.
Original entry on oeis.org
1, 1, 2, 2, 4, 5, 7, 10, 13, 17, 21, 28, 35, 46, 57, 70, 87, 110, 130, 165, 198, 238, 285, 349, 410, 498, 583, 702, 819, 983, 1136, 1353, 1570, 1852, 2137, 2520, 2898, 3390, 3891, 4540, 5191, 6028, 6889, 7951, 9082, 10450, 11884, 13650, 15508, 17728, 20113
Offset: 0
The a(1) = 1 through a(8) = 13 partitions:
(1) (2) (3) (4) (5) (6) (7) (8)
(11) (111) (22) (32) (33) (43) (44)
(31) (41) (51) (52) (53)
(1111) (311) (222) (61) (62)
(11111) (411) (322) (71)
(3111) (331) (332)
(111111) (511) (611)
(4111) (2222)
(31111) (3311)
(1111111) (5111)
(41111)
(311111)
(11111111)
For all differences of pairs parts we have
A364345.
For subsets of {1..n} instead of partitions we have
A364463.
A325325 counts partitions with distinct first-differences.
-
Table[Length[Select[IntegerPartitions[n],Intersection[#,-Differences[#]]=={}&]],{n,0,30}]
-
from collections import Counter
from sympy.utilities.iterables import partitions
def A363260(n): return sum(1 for s,p in map(lambda x: (x[0],tuple(sorted(Counter(x[1]).elements()))), partitions(n,size=True)) if set(p).isdisjoint({p[i+1]-p[i] for i in range(s-1)})) # Chai Wah Wu, Sep 26 2023
A364461
Positive integers such that if prime(a)*prime(b) is a divisor, prime(a+b) is not.
Original entry on oeis.org
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 61, 62, 64, 65, 66, 67, 68, 69, 71, 73, 74, 75, 76
Offset: 1
The prime indices of 198 are {1,2,2,5}, which is sum-free even though it is not knapsack (A299702, A299729), so 198 is in the sequence.
Subsets of this type are counted by
A085489, with re-usable parts
A007865.
Subsets not of this type are counted by
A093971, w/ re-usable parts
A088809.
Partitions of this type are counted by
A236912.
The complement allowing parts to be re-used is
A364348, counted by
A363225.
The non-binary version allowing re-used parts is counted by
A364350.
-
prix[n_]:=If[n==1,{}, Flatten[Cases[FactorInteger[n], {p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[100],Intersection[prix[#], Total/@Subsets[prix[#],{2}]]=={}&]
A364462
Positive integers having a divisor of the form prime(a)*prime(b) such that prime(a+b) is also a divisor.
Original entry on oeis.org
12, 24, 30, 36, 48, 60, 63, 70, 72, 84, 90, 96, 108, 120, 126, 132, 140, 144, 150, 154, 156, 165, 168, 180, 189, 192, 204, 210, 216, 228, 240, 252, 264, 270, 273, 276, 280, 286, 288, 300, 308, 312, 315, 324, 325, 330, 336, 348, 350, 360, 372, 378, 384, 390
Offset: 1
The terms together with their prime indices begin:
12: {1,1,2}
24: {1,1,1,2}
30: {1,2,3}
36: {1,1,2,2}
48: {1,1,1,1,2}
60: {1,1,2,3}
63: {2,2,4}
70: {1,3,4}
72: {1,1,1,2,2}
84: {1,1,2,4}
90: {1,2,2,3}
96: {1,1,1,1,1,2}
108: {1,1,2,2,2}
120: {1,1,1,2,3}
126: {1,2,2,4}
132: {1,1,2,5}
140: {1,1,3,4}
144: {1,1,1,1,2,2}
Subsets not of this type are counted by
A085489, w/ re-usable parts
A007865.
Subsets of this type are counted by
A088809, with re-usable parts
A093971.
Partitions not of this type are counted by
A236912.
Partitions of this type are counted by
A237113.
-
filter:= proc(n) local F, i,j,m;
F:= map(t -> `if`(t[2]>=2, numtheory:-pi(t[1])$2, numtheory:-pi(t[1])), ifactors(n)[2]);
for i from 1 to nops(F)-1 do for j from 1 to i-1 do
if member(F[i]+F[j],F) then return true fi
od od;
false
end proc:
select(filter, [$1..1000]); # Robert Israel, Aug 30 2023
-
prix[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[100],Intersection[prix[#], Total/@Subsets[prix[#],{2}]]!={}&]
A364348
Numbers with two possibly equal divisors prime(a) and prime(b) such that prime(a+b) is also a divisor.
Original entry on oeis.org
6, 12, 18, 21, 24, 30, 36, 42, 48, 54, 60, 63, 65, 66, 70, 72, 78, 84, 90, 96, 102, 105, 108, 114, 120, 126, 130, 132, 133, 138, 140, 144, 147, 150, 154, 156, 162, 165, 168, 174, 180, 186, 189, 192, 195, 198, 204, 210, 216, 222, 228, 231, 234, 240, 246, 252
Offset: 1
We have 6 because prime(1) and prime(1) are both divisors of 6, and prime(1+1) is also.
The terms together with their prime indices begin:
6: {1,2}
12: {1,1,2}
18: {1,2,2}
21: {2,4}
24: {1,1,1,2}
30: {1,2,3}
36: {1,1,2,2}
42: {1,2,4}
48: {1,1,1,1,2}
54: {1,2,2,2}
60: {1,1,2,3}
63: {2,2,4}
65: {3,6}
66: {1,2,5}
70: {1,3,4}
72: {1,1,1,2,2}
-
prix[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[100],Intersection[prix[#],Total/@Tuples[prix[#],2]]!={}&]
A364533
Number of strict integer partitions of n containing the sum of no pair of distinct parts. A variation of sum-free strict partitions.
Original entry on oeis.org
1, 1, 1, 2, 2, 3, 3, 5, 5, 8, 7, 11, 11, 15, 15, 21, 22, 28, 32, 38, 40, 51, 55, 65, 74, 83, 94, 111, 119, 136, 160, 174, 196, 222, 252, 273, 315, 341, 391, 425, 477, 518, 602, 636, 719, 782, 886, 944, 1073, 1140, 1302, 1380, 1553, 1651, 1888, 1995, 2224, 2370
Offset: 0
The a(1) = 1 through a(12) = 11 partitions (A..C = 10..12):
1 2 3 4 5 6 7 8 9 A B C
21 31 32 42 43 53 54 64 65 75
41 51 52 62 63 73 74 84
61 71 72 82 83 93
421 521 81 91 92 A2
432 631 A1 B1
531 721 542 543
621 632 732
641 741
731 831
821 921
Allowing re-used parts gives
A364346.
The linear combination-free version is
A364350.
The complement in strict partitions is
A364670, w/ re-used parts
A363226.
-
Table[Length[Select[IntegerPartitions[n], UnsameQ@@#&&Intersection[#, Total/@Subsets[#,{2}]] == {}&]],{n,0,30}]
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