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 1-10 of 13 results. Next

A122172 Triangle read by rows relating A074139, A074141, A078436 and A079025.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 3, 3, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 2, 3, 2, 1, 1, 3, 4, 3, 1, 1, 4, 6, 4, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 2, 3, 3, 2, 1, 1, 3, 4, 4, 3, 1, 1, 3, 5, 5, 3, 1, 1, 4, 7, 7, 4, 1, 1, 5, 10, 10, 5, 1, 1, 1, 1, 1, 1, 1, 1
Offset: 0

Views

Author

Alford Arnold, Aug 23 2006

Keywords

Comments

A proper definition is needed for this sequence.
Are the row sums A074139(n) and the row lengths A000041(n)? - R. J. Mathar, May 08 2019 [Not exactly: see below. - M. F. Hasler, Jan 07 2024]
From M. F. Hasler, Jan 06 2024: (Start)
I get this triangle as T(n,k) = # { v in S(p_n), |v| = k }, where p_n is the n-th partition as listed in A036036 or A036037 (which has a nice table of the p's), and S(p) = {0, ..., p[1]} x ... x {0, ..., p[#p]}, the set of vectors v with 0 <= v[i] <= p[i] for all indices i from 1 to #p = number of parts in p.
Then the row sums are indeed the total number of elements in S(p_n) which is equal to the product (p[1]+1)*...*(p[#p]+1) which is also the number of divisors of the Heinz number of p (cf. A185974).
The row lengths are 1 + |p| = 1 + sum of all parts of p (corresponding to the possible values of |v| ranging from 0 to |p|), repeated A000041(|p|) times: A000041(0) = 1 row of length 0+1 for the partition () of 0, A000041(1) = 1 row of length 1+1 for partition (1) of 1; A000041(2) = 2 rows of length 2+1 for the two partitions (2) and (1,1) of 2; A000041(3) = 3 rows of length 3+1 for the 3 partitions {(3), (2,1), (1,1,1)} of 3; etc. (End)

Examples

			The triangle begins:
  1
  1 1
  1 1 1
  1 2 1
  1 1 1 1
  1 2 2 1
  1 3 3 1
  1 1 1 1 1
  1 2 2 2 1
  1 2 3 2 1
  1 3 4 3 1
  1 4 6 4 1
  1 1 1 1 1 1
  1 2 2 2 2 1
  1 2 3 3 2 1
  1 3 4 4 3 1
  1 3 5 5 3 1
  1 4 7 7 4 1
  1 5 10 10 5 1
		

Crossrefs

Cf. A036036 (partitions in A-S order), A036037 (the same, parts reversed), A185974 (corresponding Heinz numbers).

Programs

  • PARI
    A122172_row(n, p=part(n))={my(c=Vec(0, vecsum(p)+1)); forvec(v=[[0, k]| k<-p], c[vecsum(v)+1]++); c} \\ instead of n one can directly give p as 2nd arg
    /* helper function: n-th partition as listed in A036036, A036037 or A185974 */
    part(n)={my(c, r=0); while(n >= c = numbpart(r), n -= c; r++); partitions(r)[n+1]}
    for(n=0,5, forpart(p=n, print(A122172_row(, Vec(p))) )) \\ Illustration. \\ M. F. Hasler, Jan 06 2024

Extensions

More terms from M. F. Hasler, Jan 07 2024

A122453 Triangular array related to A122402 as A079025 relates to A122172; sums A079139 values associated with cyclic partitions.

Original entry on oeis.org

1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 3, 2, 2, 3, 4, 4, 3, 2, 4, 8, 13, 15, 13, 8, 4, 4, 8, 13, 16, 16, 13, 8, 4, 7, 17, 32, 45, 51, 45, 32, 17, 7, 8, 20, 38, 56, 67, 67, 56, 38, 20, 8, 12, 34, 72, 117, 156, 171, 156, 117, 72, 34, 12, 14, 41, 88, 147, 203, 237, 237, 203, 147, 88, 41
Offset: 0

Views

Author

Alford Arnold, Sep 07 2006

Keywords

Examples

			The table begins:
1
0 0
1 1 1
1 1 1 1
2 3 4 3 2
2 3 4 4 3 2
4 8 13 15 13 8 4
4 8 13 16 16 13 8 4
7 17 32 45 51 45 32 17 7
8 20 38 56 67 67 56 38 20 8
12 34 72 117 156 171 156 117 72 34 12
14 41 88 147 203 237 237 203 147 88 41 14
		

Crossrefs

A074141 Sum of products of parts increased by 1 in all partitions of n.

Original entry on oeis.org

1, 2, 7, 18, 50, 118, 301, 684, 1621, 3620, 8193, 17846, 39359, 84198, 181313, 383208, 811546, 1695062, 3546634, 7341288, 15207022, 31261006, 64255264, 131317012, 268336125, 545858260, 1110092387, 2250057282, 4558875555, 9213251118, 18613373708, 37529713890
Offset: 0

Views

Author

Amarnath Murthy, Aug 28 2002

Keywords

Comments

Replace each term in A036035 by the number of its divisors as in A074139; sequence gives sum of terms in the n-th row.
This is the sum of the number of submultisets of the multisets with n elements; a part of a partition is a frequency of such an element. - George Beck, Nov 01 2011

Examples

			The partitions of 4 are 4, 3+1, 2+2, 2+1+1, 1+1+1+1, the corresponding products when parts are increased by 1 are 5,8,9,12,16 and their sum is a(4) = 50.
		

Crossrefs

Row sums of A074139 and of A079025 and of A079308 and of A238963.
Column k=2 of A261718.
Cf. A267008.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0 or i=1,
          2^n, b(n, i-1) +(1+i)*b(n-i, min(n-i, i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..50); # Alois P. Heinz, Sep 07 2014
  • Mathematica
    Table[Plus @@ Times @@@ (IntegerPartitions[n] + 1), {n, 0, 28}] (* T. D. Noe, Nov 01 2011 *)
    b[n_, i_] := b[n, i] = If[n==0, 1, If[i<1, 0, b[n, i-1] + If[i>n, 0, (1+i) * b[n-i, i]]]]; a[n_] := b[n, n]; Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Oct 08 2015, after Alois P. Heinz *)
  • Maxima
    S(n,m):=if n=0 then 1 else if nVladimir Kruchinin, Sep 07 2014 */

Formula

G.f.: 1/Product_{m>0} (1-(m+1)*x^m).
a(n) = 1/n*Sum_{k=1..n} b(k)*a(n-k), where b(k) = Sum_{d divides k} d*(d+1)^(k/d).
a(n) = S(n,1), where S(n,m) = sum(k=m..n/2, (k+1)*S(n-k,k))+(n+1), S(n,n)=n+1, S(0,m)=1, S(n,m)=0 for nVladimir Kruchinin, Sep 07 2014
a(n) ~ c * 2^n, where c = Product_{k>=2} 1/(1-(k+1)/2^k) = 18.56314656361011472747535423226928404842588594722907068201... = A256155. - Vaclav Kotesovec, Sep 11 2014, updated May 10 2021

Extensions

More terms from Alford Arnold, Sep 17 2002
More terms, better description and formulas from Vladeta Jovovic, Vladimir Baltic, Nov 28 2002

A309691 Total number of divisors d of m (counted with multiplicity), such that the prime signature of d is a partition of two and m runs through the set of least numbers whose prime signature is a partition of n.

Original entry on oeis.org

2, 6, 16, 32, 65, 113, 199, 323, 523, 803, 1237, 1826, 2696, 3873, 5544, 7767, 10859, 14912, 20425, 27598, 37156, 49473, 65679, 86350, 113179, 147191, 190806, 245676, 315415, 402522, 512250, 648551, 818831, 1029139, 1290151, 1610701, 2005969, 2489167, 3081434
Offset: 2

Views

Author

Alois P. Heinz, Aug 23 2019

Keywords

Crossrefs

Column k=2 of A079025.

A309693 Total number of divisors d of m (counted with multiplicity), such that the prime signature of d is a partition of three and m runs through the set of least numbers whose prime signature is a partition of n.

Original entry on oeis.org

3, 12, 32, 79, 160, 318, 573, 1013, 1683, 2776, 4366, 6820, 10325, 15503, 22721, 33105, 47289, 67177, 93990, 130747, 179636, 245613, 332243, 447368, 597142, 793508, 1046512, 1374713, 1793842, 2332053, 3014392, 3882511, 4975306, 6354950, 8079980, 10241877
Offset: 3

Views

Author

Alois P. Heinz, Aug 23 2019

Keywords

Crossrefs

Column k=3 of A079025.

A309915 Total number of divisors d of m (counted with multiplicity), such that the prime signature of d is a partition of n and m runs through the set of least numbers whose prime signature is a partition of 2n.

Original entry on oeis.org

1, 3, 16, 79, 371, 1683, 7413, 31769, 133692, 553848, 2265776, 9181670, 36928673, 147650125, 587734595, 2331625130, 9226486717, 36443758767, 143763811785, 566624864014, 2232055573265, 8789903797692, 34610963678036, 136287108614677, 536724439657635
Offset: 0

Views

Author

Alois P. Heinz, Aug 22 2019

Keywords

Examples

			a(2) = 16: The partitions of 2*2 are (4), (31), (22), (211), (1111). Least numbers with these prime signatures are 16, 24, 36, 60, 210. Their divisors with prime signatures (2) or (11) are {4}, {4,6}, {4,6,9}, {4,6,10,15}, {6,10,14,15,21,35}. The total number is 1 + 2 + 3 + 4 + 6.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; expand(`if`(n=0 or i=1, (x+1)^n,
          b(n, i-1) +factor((x^(i+1)-1)/(x-1))*b(n-i, min(n-i, i))))
        end:
    a:= n-> coeff(b(2*n$2), x, n):
    seq(a(n), n=0..25);
  • Mathematica
    b[n_, i_] := b[n, i] = Expand[If[n == 0 || i == 1, (x + 1)^n, b[n, i - 1] + Factor[(x^(i + 1) - 1)/(x - 1)] b[n - i, Min[n - i, i]]]];
    a[n_] := Coefficient[b[2n, 2n], x, n];
    a /@ Range[0, 25] (* Jean-François Alcover, Dec 12 2020, after Alois P. Heinz *)

Formula

a(n) = A079025(2n,n).

A309919 Total number of divisors d of m (counted with multiplicity), such that the prime signature of d is a partition of four and m runs through the set of least numbers whose prime signature is a partition of n.

Original entry on oeis.org

5, 20, 65, 160, 371, 756, 1485, 2701, 4822, 8144, 13558, 21756, 34449, 53044, 80874, 120573, 178215, 258897, 373069, 530068, 748026, 1043001, 1445321, 1983124, 2705411, 3659491, 4924840, 6578409, 8746089, 11553224, 15194682, 19870115, 25881012, 33537548
Offset: 4

Views

Author

Alois P. Heinz, Aug 23 2019

Keywords

Crossrefs

Column k=4 of A079025.

A309920 Total number of divisors d of m (counted with multiplicity), such that the prime signature of d is a partition of five and m runs through the set of least numbers whose prime signature is a partition of n.

Original entry on oeis.org

7, 35, 113, 318, 756, 1683, 3405, 6662, 12205, 21840, 37415, 62866, 102248, 163920, 256132, 395419, 598461, 896112, 1320378, 1928165, 2777751, 3970068, 5610839, 7872981, 10941361, 15109772, 20691740, 28174131, 38084160, 51210142, 68419073, 90977599, 120279526
Offset: 5

Views

Author

Alois P. Heinz, Aug 23 2019

Keywords

Crossrefs

Column k=5 of A079025.

A309921 Total number of divisors d of m (counted with multiplicity), such that the prime signature of d is a partition of six and m runs through the set of least numbers whose prime signature is a partition of n.

Original entry on oeis.org

11, 54, 199, 573, 1485, 3405, 7413, 14901, 28943, 53365, 95822, 165612, 280689, 461838, 747905, 1183801, 1848372, 2833288, 4294109, 6408566, 9470481, 13817889, 19985430, 28592582, 40594736, 57092122, 79745667, 110478215, 152106462, 207912108, 282607366
Offset: 6

Views

Author

Alois P. Heinz, Aug 23 2019

Keywords

Crossrefs

Column k=6 of A079025.

A309922 Total number of divisors d of m (counted with multiplicity), such that the prime signature of d is a partition of seven and m runs through the set of least numbers whose prime signature is a partition of n.

Original entry on oeis.org

15, 86, 323, 1013, 2701, 6662, 14901, 31769, 63626, 123049, 227506, 410058, 714139, 1218779, 2025892, 3310989, 5298045, 8360139, 12962789, 19860393, 29990209, 44815019, 66147220, 96748294, 140005126, 200971214, 285833838, 403589570, 565249022, 786529323
Offset: 7

Views

Author

Alois P. Heinz, Aug 23 2019

Keywords

Crossrefs

Column k=7 of A079025.
Showing 1-10 of 13 results. Next