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 1-4 of 4 results.

A300632 Expansion of e.g.f. exp(x + Sum_{k>=2} prime(k-1)*x^k/k!).

Original entry on oeis.org

1, 1, 3, 10, 42, 203, 1119, 6839, 45895, 334142, 2619052, 21946647, 195537777, 1843619725, 18321431155, 191242913022, 2090436115146, 23864653888881, 283865214366771, 3510656353388517, 45056394441558593, 599057016471131604, 8238406603745152620, 117020080948487107289
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 10 2018

Keywords

Comments

Exponential transform of A008578.

Examples

			E.g.f.: A(x) = 1 + x/1! + 3*x^2/2! + 10*x^3/3! + 42*x^4/4! + 203*x^5/5! + 1119*x^6/6! + 6839*x^7/7! + ..
		

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; (p-> `if`(n=0, 1, add(a(n-j)*p(j)*
          binomial(n-1, j-1), j=1..n)))(t-> `if`(t=1, 1, ithprime(t-1)))
        end:
    seq(a(n), n=0..25);  # Alois P. Heinz, Mar 10 2018
  • Mathematica
    nmax = 23; CoefficientList[Series[Exp[x + Sum[Prime[k - 1] x^k/k!, {k, 2, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
    p[1] = 1; p[n_] := p[n] = Prime[n - 1]; a[n_] := a[n] = Sum[p[k] Binomial[n - 1, k - 1] a[n - k], {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 23}]

Formula

E.g.f.: exp(Sum_{k>=1} A008578(k)*x^k/k!).

A300662 Expansion of 1/(1 - x - Sum_{k>=2} prime(k-1)*x^k).

Original entry on oeis.org

1, 1, 3, 8, 22, 59, 160, 429, 1155, 3105, 8354, 22474, 60457, 162636, 437509, 1176941, 3166097, 8517138, 22912002, 61635707, 165806564, 446037175, 1199887133, 3227823181, 8683185454, 23358686444, 62837334885, 169039070970, 454732963567, 1223279724439, 3290751724917
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 10 2018

Keywords

Comments

Invert transform of A008578.

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, add(
         `if`(j=1, 1, ithprime(j-1))*a(n-j), j=1..n))
        end:
    seq(a(n), n=0..35);  # Alois P. Heinz, Mar 10 2018
  • Mathematica
    nmax = 30; CoefficientList[Series[1/(1 - x - Sum[Prime[k - 1] x^k, {k, 2, nmax}]), {x, 0, nmax}], x]
    p[1] = 1; p[n_] := p[n] = Prime[n - 1]; a[n_] := a[n] = Sum[p[k] a[n - k], {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 30}]

Formula

G.f.: 1/(1 - Sum_{k>=1} A008578(k)*x^k).

A050513 a(n) = (-1)^n * Sum_{i=0..n} binomial(n+1,i+1)*prime(i+1).

Original entry on oeis.org

2, -7, 20, -53, 136, -341, 836, -2005, 4712, -10881, 24770, -55763, 124464, -275933, 608282, -1334119, 2911870, -6325091, 13674120, -29425307, 63042232, -134517425, 285984130, -606056545, 1280778342, -2700105565, 5680099084, -11925792491
Offset: 0

Views

Author

N. J. A. Sloane, Dec 28 1999

Keywords

Crossrefs

Cf. A030015.

Programs

  • Mathematica
    Table[(-1)^(n-1)*Sum[Binomial[n, k]*Prime[k], {k, 1, n}], {n, 1, 20}] (* Vaclav Kotesovec, Mar 01 2016 *)

A333176 a(n) = Sum_{k=1..n} (binomial(n,k) mod 2) * prime(k).

Original entry on oeis.org

2, 3, 10, 7, 20, 23, 58, 19, 44, 51, 112, 63, 140, 151, 328, 53, 114, 117, 250, 131, 276, 287, 604, 161, 342, 355, 742, 383, 798, 825, 1720, 131, 270, 273, 566, 289, 596, 607, 1252, 323, 664, 675, 1392, 711, 1458, 1481, 3046, 407, 832, 839, 1718, 875, 1782
Offset: 1

Views

Author

Ilya Gutkovskiy, Mar 10 2020

Keywords

Crossrefs

Programs

  • Maple
    N:= 200: # for a(1) .. a(N)
    P:= [seq(ithprime(i),i=1..N)]:
    B:= [1,1]: R:= 2:
    for n from 2 to N do
      B:= [1,op(B[2..-1]+B[1..-2] mod 2),1];
      R:= R, convert(P[select(t -> B[t+1] = 1,[$1..n])],`+`);
    od:
    R; # Robert Israel, Jan 29 2025
  • Mathematica
    Table[Sum[Mod[Binomial[n, k], 2] Prime[k], {k, 1, n}], {n, 1, 53}]
  • PARI
    a(n) = sum(k=1, n, if (binomial(n, k) % 2, prime(k))); \\ Michel Marcus, Mar 10 2020
    
  • Python
    from sympy import prime
    def A333176(n): return sum(prime(k) for k in range(1,n+1) if not ~n&k) # Chai Wah Wu, Jul 22 2025

Formula

Sum_{k=1..n} (-1)^A010060(n-k) * (binomial(n,k) mod 2) * a(k) = prime(n).
Showing 1-4 of 4 results.