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.

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A074140 Sum of least integers of prime signatures over all partitions of n.

Original entry on oeis.org

1, 2, 10, 50, 346, 3182, 38770, 609290, 11226106, 250148582, 7057182250, 216512001950, 7903965900226, 321552174623162, 13779150603234010, 644574260638821590, 33968684108427733426, 1994885097404292104942, 121496572792097514728530, 8114030083731371137603190
Offset: 0

Views

Author

Amarnath Murthy, Aug 28 2002

Keywords

Comments

Old name was: Sum of terms in n-th group in A036035.
a(n) is also the sum of terms in n-th row of A063008, A087443 or A227955.

Examples

			a(6) = 64+96+144+216+240+360+900+840+1260+4620+30030 = 38770.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i, j) option remember;
          `if`(n=0, 1, `if`(i<1, 0, b(n, i-1, j)+
          `if`(i>n, 0, ithprime(j)^i*b(n-i, i, j+1))))
        end:
    a:= n-> b(n$2, 1):
    seq(a(n), n=0..40);  # Alois P. Heinz, Aug 03 2013
  • Mathematica
    b[n_, i_, j_] := b[n, i, j] = If[n == 0, 1, If[i<1, 0, b[n, i-1, j]+If[i>n, 0, Prime[j]^i*b[n-i, i, j+1]]]]; a[n_] := b[n, n, 1]; Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Feb 25 2014, after Alois P. Heinz *)
  • Sage
    def A074140(n):
        L = []
        P = primes_first_n(n)
        for p in Partitions(n):
            m = mul(P[i]^pi for i, pi in enumerate(p))
            L.append(m)
        return add(L)
    [A074140(n) for n in (0..20)]  # Peter Luschny, Aug 02 2013

Extensions

More terms from Alford Arnold, Sep 10 2002
a(10)-a(12) from Thomas A. Rockwell (LlewkcoRAT(AT)aol.com), Sep 30 2004
a(12) corrected by Peter Luschny, Aug 03 2013
New name from Alois P. Heinz, Aug 03 2013

A328524 T(n,k) is the k-th smallest least integer of prime signatures for partitions of n into distinct parts; triangle T(n,k), n>=0, 1<=k<=A000009(n), read by rows.

Original entry on oeis.org

1, 2, 4, 8, 12, 16, 24, 32, 48, 72, 64, 96, 144, 360, 128, 192, 288, 432, 720, 256, 384, 576, 864, 1440, 2160, 512, 768, 1152, 1728, 2592, 2880, 4320, 10800, 1024, 1536, 2304, 3456, 5184, 5760, 8640, 12960, 21600, 75600, 2048, 3072, 4608, 6912, 10368, 11520
Offset: 0

Views

Author

Alois P. Heinz, Feb 18 2020

Keywords

Examples

			Triangle T(n,k) begins:
     1;
     2;
     4;
     8,   12;
    16,   24;
    32,   48,   72;
    64,   96,  144,  360;
   128,  192,  288,  432,  720;
   256,  384,  576,  864, 1440, 2160;
   512,  768, 1152, 1728, 2592, 2880, 4320, 10800;
  1024, 1536, 2304, 3456, 5184, 5760, 8640, 12960, 21600, 75600;
  ...
		

Crossrefs

Column k=1-3 give: A000079, A003945 for n>2, A116453 for n>4.
Row sums give A332626.
Last elements of rows give A332644.
Cf. A000009, A087443 (for all partitions), A087980 (as sorted sequence).

Programs

  • Maple
    b:= proc(n, i, j) option remember; `if`(i*(i+1)/2 x*ithprime(j)^i,
           b(n-i, min(n-i, i-1), j+1))[], b(n, i-1, j)[]]))
        end:
    T:= n-> sort(b(n$2, 1))[]:
    seq(T(n), n=0..12);
  • Mathematica
    b[n_, i_, j_] := b[n, i, j] = If[i(i+1)/2 < n, {}, If[n == 0, {1}, Join[# * Prime[j]^i& /@ b[n - i, Min[n - i, i - 1], j + 1], b[n, i - 1, j]]]];
    T[n_] := Sort[b[n, n, 1]];
    Table[T[n], {n, 0, 12}] // Flatten (* Jean-François Alcover, May 07 2020, after Maple *)
Showing 1-2 of 2 results.