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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A343944 Total number of parts in all partitions of n into powers of 2: p1 <= p2 <= ... <= p_k such that p_i <= 1 + Sum_{j=1..i-1} p_j.

Original entry on oeis.org

0, 1, 2, 5, 7, 12, 15, 29, 35, 50, 58, 86, 98, 128, 143, 225, 251, 318, 350, 453, 495, 603, 653, 846, 914, 1092, 1172, 1419, 1517, 1773, 1886, 2521, 2687, 3130, 3322, 3917, 4147, 4759, 5021, 5909, 6227, 7082, 7442, 8537, 8955, 10076, 10544, 12326, 12898, 14452
Offset: 0

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Author

Alois P. Heinz, May 04 2021

Keywords

Examples

			a(5) = 12 = 5+4+3: [1,1,1,1,1], [1,1,1,2], [1,2,2].
a(6) = 15 = 6+5+4: [1,1,1,1,1,1], [1,1,1,1,2], [1,1,2,2].
a(7) = 29 = 7+6+5+4+4+3: [1,1,1,1,1,1,1], [1,1,1,1,1,2], [1,1,1,2,2], [1,2,2,2], [1,1,1,4], [1,2,4].
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, [1, 0], `if`(i<0, 0, (p-> `if`(
           p>n or p>n-p+1, 0, (h-> h+[0, h[1]])(b(n-p, i))))(2^i)+b(n, i-1)))
        end:
    a:= n-> b(n, ilog2(n))[2]:
    seq(a(n), n=0..60);
  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0, {1, 0}, If[i < 0, {0, 0}, Function[p, If[p > n || p > n - p + 1, {0, 0}, Function[h, h + {0, h[[1]]}][b[n - p, i]]]][2^i] + b[n, i - 1]]];
    a[n_] := b[n, Floor@Log2[n]][[2]];
    Table[a[n], {n, 0, 60}] (* Jean-François Alcover, Nov 16 2022, after Alois P. Heinz *)

A304909 Expansion of x * (d/dx) Product_{k>=0} 1/(1 - x^(2^k)).

Original entry on oeis.org

0, 1, 4, 6, 16, 20, 36, 42, 80, 90, 140, 154, 240, 260, 364, 390, 576, 612, 828, 874, 1200, 1260, 1628, 1702, 2256, 2350, 2964, 3078, 3920, 4060, 4980, 5146, 6464, 6666, 8092, 8330, 10224, 10508, 12540, 12870, 15600, 15990, 18900, 19350, 23056, 23580, 27508, 28106, 33216, 33908
Offset: 0

Views

Author

Ilya Gutkovskiy, May 20 2018

Keywords

Comments

Sum of all parts of all partitions of n into powers of 2.
Convolution of the sequences A018819 and A038712.

Crossrefs

Programs

  • Mathematica
    nmax = 49; CoefficientList[Series[x D[Product[1/(1 - x^2^k), {k, 0, Floor[Log[nmax]/Log[2]] + 1}], x], {x, 0, nmax}], x]
    nmax = 49; CoefficientList[Series[x D[Product[(1 + x^2^k)^(k + 1), {k, 0, Floor[Log[nmax]/Log[2]] + 1}], x], {x, 0, nmax}], x]
    a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d Boole[d == 2^IntegerExponent[d, 2]], {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[n a[n], {n, 0, 49}]

Formula

G.f.: x * (d/dx) Product_{k>=0} (1 + x^(2^k))^(k+1).
G.f.: Sum_{i>=0} 2^i*x^(2^i)/(1 - x^(2^i)) * Product_{j>=0} 1/(1 - x^(2^j)).
a(n) = n*A018819(k).
Showing 1-2 of 2 results.