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.

Previous Showing 51-57 of 57 results.

A132858 Composite "antimutinous" numbers. An antimutinous number is an integer m > 1 where m/p^k < p, where p is the largest prime divisor of m and p^k is the largest power of p dividing m.

Original entry on oeis.org

4, 6, 8, 9, 10, 14, 15, 16, 18, 20, 21, 22, 25, 26, 27, 28, 32, 33, 34, 35, 38, 39, 42, 44, 46, 49, 50, 51, 52, 54, 55, 57, 58, 62, 64, 65, 66, 68, 69, 74, 75, 76, 77, 78, 81, 82, 85, 86, 87, 88, 91, 92, 93, 94, 95, 98, 99, 100, 102, 104, 106, 110, 111, 114, 115, 116, 117, 118
Offset: 1

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Author

Leroy Quet, Nov 21 2007

Keywords

Comments

{a(k)-1} is the complement of sequence A056077. In other words, {a(k)} contains precisely those positive integers m where A001142(m-1) (= product{k=1 to m-1} k^(2k-m)) is not divisible by all primes <= m-1.

Crossrefs

Programs

  • Mathematica
    antiQ[n_] := Module[{f = FactorInteger[n], p, k}, p = f[[-1, 1]]; k = f[[-1, 2]]; n/p^k < p]; Select[Range[118], CompositeQ[#] && antiQ[#] &] (* Amiram Eldar, Feb 24 2020 *)

Extensions

Extended by Ray Chandler, Nov 17 2008

A260610 Suprafactorials: Product of first n hyperfactorials divided by the product of the first n superfactorials.

Original entry on oeis.org

1, 1, 2, 18, 1728, 4320000, 699840000000, 18525482136000000000, 204051433560311070720000000000, 2399547398533110254947300351672320000000000, 77759951835586717141477466390085274435584000000000000000000, 18011357710498321908881994832212360081640749122627567616000000000000000000000000
Offset: 0

Views

Author

Matthew Campbell, Jul 30 2015

Keywords

Examples

			a(3) = (Hyperfactorial(3)/Superfactorial(3)) * (Hyperfactorial(2)/Superfactorial(2)) * (Hyperfactorial(1)/Superfactorial(1)) * (Hyperfactorial(0)/Superfactorial(0)) = ((3^3 * 2^2 * 1^1)/(3! * 2! * 1!)) * ((2^2 * 1^1)/(2!*1!)) * (1^1/1!) * 1 = ((27 * 4)/(6 * 2)) * (4/2) * 1 = (108/12) * (4/2) = 9 * 2 = 18.
		

Crossrefs

Programs

  • Mathematica
    Table[Product[Hyperfactorial[n]/BarnesG[n+2], {n, 0, m}], {m, 0, 12}]
    Table[BarnesG[n+2]^(n-1) / Product[BarnesG[k]^3, {k, 1, n + 1}], {n, 0, 12}] (* Vaclav Kotesovec, Nov 19 2023 *)
  • PARI
    a001142(n) = prod(m=1, n, binomial(n, m));
    a(n) = prod(k=0, n, a001142(k)); \\ Michel Marcus, Aug 06 2015

Formula

a(n) = A125760(n)/A055462(n).
a(n) = Product_{k=0..n} A001142(k).
a(n) = Product_{k=0..n} hyperfactorial(k)/superfactorial(k).
a(n) = Product_{i=1..n} (Product_{j=1..i} binomial(i,j)). - Pedro Caceres, Apr 13 2019
From Vaclav Kotesovec, Nov 19 2023: (Start)
a(n) = BarnesG(n+2)^(n-1) / Product_{k=1..n+1} BarnesG(k)^3.
a(n) ~ A^(2*n + 5/2) * exp(n^3/6 + 7*n^2/8 + 5*n/6 - 3*zeta(3)/(8*Pi^2) - 1/8) / ((2*Pi)^(n^2/4 + 3*n/4 + 1/2) * n^(n^2/4 + 7*n/12 + 7/24)), where A is the Glaisher-Kinkelin constant A074962. (End)

A304902 Let (P,<) be the strict partial order on the subsets of {1,2,...,n} ordered by their cardinality. Then a(n) is the number of paths of any length from {} to {1,2,...,n}.

Original entry on oeis.org

1, 1, 3, 16, 175, 4356, 263424, 40144896, 15714084159, 15953234222500, 42223789335548788, 292262228709213966336, 5302397936652484482131200, 252622720869371754406993137664, 31660291085217875120800516475520000, 10454334647424614439930776175842716286976
Offset: 0

Views

Author

Geoffrey Critzer, May 20 2018

Keywords

Comments

A001142 counts such paths of length n.
A000670 counts such paths under the inclusion relation.

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k=0, 1,
          add(b(n, j), j=0..k-1)*binomial(n, k))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..17);  # Alois P. Heinz, May 20 2018
  • Mathematica
    Table[f[list_] := Apply[Times, Map[Binomial[n, #] &, list]];
    Total[Map[f, Map[Accumulate,Level[Map[Permutations, Partitions[n]], {2}]]]], {n, 0, 15}]

A334038 a(n) = Product_{p<=n, p prime} binomial(n,p).

Original entry on oeis.org

1, 1, 1, 3, 24, 100, 1800, 15435, 702464, 13716864, 163296000, 1383574500, 109294479360, 3842829083808, 1159801183597056, 132320316074821875, 8213884352593920000, 327816138093181337600, 167079259535068179726336, 34044607357920579594754944
Offset: 0

Views

Author

Om R. Patel, Apr 13 2020

Keywords

Examples

			For n=2, p=2: a(n) = C(2,2) = 1.
For n=3, p=2,3: a(n) = C(3,2) * C(3,3) = 3.
For n=4, p=2,3: a(n) = C(4,2) * C(4,3) = 24.
		

Crossrefs

Programs

  • Maple
    a:= n-> mul(`if`(isprime(p), binomial(n, p), 1), p=2..n):
    seq(a(n), n=0..20);  # Alois P. Heinz, Apr 13 2020
  • PARI
    a(n) = prod(k=1, n, if (isprime(k), binomial(n, k), 1)); \\ Michel Marcus, Apr 13 2020
    
  • PARI
    a(n)=my(s); forprime(p=2,n, s*=binomial(n,p)); s \\ Charles R Greathouse IV, Apr 13 2020

A191510 Product of terms in n-th row of A132818.

Original entry on oeis.org

1, 9, 648, 360000, 1518750000, 48243443062500, 11480517255997440000, 20400479323264014247526400, 270090559531318533654528000000000, 26599911685677709861296622500000000000000, 19464564507161243794359748945629699456000000000000
Offset: 1

Views

Author

Harlan J. Brothers, Jun 04 2011

Keywords

Comments

Lim_{n -> inf} (a(n)*a(n+2))/a(n+1)^2 = e^2. Like A168510, this limit is asymptotic from above.

Examples

			For n=3, row 3 of A132818 = {6,18,6} and a(3)=648.
		

Crossrefs

Cf. A132818, A002457. Related to e as in the cases of A168510 and A001142.

Programs

  • Mathematica
    Table[Product[Product[((k + 1)/(k - 1))^k, {k, 2, j}], {j, 1, n}], {n, 1, 11}]
    Table[(n + 1)^n * Hyperfactorial[n]^2 / (2^n * BarnesG[n+2]^2), {n, 1, 12}] (* Vaclav Kotesovec, Jul 11 2015 *)

Formula

a(n)=product[product[((k + 1)/(k - 1))^k, {k, 2, j}], {j, 1, n}].
a(n) ~ A^4 * exp(n^2 + 2*n + 5/6) / (n^(2/3) * 2^(2*n+1) * Pi^(n+1)), where A = A074962 = 1.2824271291... is the Glaisher-Kinkelin constant. - Vaclav Kotesovec, Jul 11 2015

A265944 Absolute value of the determinant of the matrix whose terms are fibonacci(m+r+s)^(n) with 0 <= r, s <=n, for any m.

Original entry on oeis.org

1, 2, 36, 13824, 324000000, 1209323520000000, 1923567501916569600000000, 3436011282355888738787131392000000000, 18204541483393435808637499286914987185930240000000000, 753091424970084722185225494963366011108371967508480000000000000000000000
Offset: 1

Views

Author

Michel Marcus, Dec 23 2015

Keywords

Crossrefs

Programs

  • PARI
    a(n) = prod(j=0, n, binomial(n, j)) * prod(j=1,n, fibonacci(j)^(n-j+1))^2;

Formula

a(n) = (Product_{j=0..n} binomial(n,j)) * (Product_{j=1..n} fibonacci(j)^(n-j+1))^2.
a(n) = A001142(n)*A152686(n)^2.

A355635 Triangle read by rows. Row n gives the coefficients of Product_{k=0..n-1} (x - binomial(n-1,k)) expanded in decreasing powers of x, with row 0 = {1}.

Original entry on oeis.org

1, 1, -1, 1, -2, 1, 1, -4, 5, -2, 1, -8, 22, -24, 9, 1, -16, 93, -238, 256, -96, 1, -32, 386, -2180, 5825, -6500, 2500, 1, -64, 1586, -19184, 117561, -345600, 407700, -162000, 1, -128, 6476, -164864, 2229206, -15585920, 51583084, -64538880, 26471025
Offset: 0

Views

Author

Thomas Scheuerle, Jul 11 2022

Keywords

Comments

Without signs the triangle of elementary symmetric functions of the terms binomial(n,j), j=0..n.

Examples

			The triangle begins:
  1;
  1,  -1;
  1,  -2,   1;
  1,  -4,   5,    -2;
  1,  -8,  22,   -24,    9;
  1, -16,  93,  -238,  256,   -96;
  1, -32, 386, -2180, 5825, -6500, 2500;
  ...
Row 4: x^4 - 8*x^3 + 22*x^2 - 24*x + 9 = (x-1)*(x-4)*(x-6)*(x-4)*(x-1).
		

Crossrefs

Cf. A001142 (right diagonal unsigned).

Programs

  • PARI
    T(n, k) = polcoeff(prod(m=0, n, (x-binomial(n-1, m))), n-k+1);

Formula

T(n, 0) = 1.
T(n, 1) = -2^(n-1), for n > 0.
T(n, 2) = A000346(n-2), for n > 1.
T(n, 3) = -A025131(n-1), for n > 1.
T(n, 4) = A025133(n-1), for n > 1.
T(n, n) = (-1)^n*A001142(n-1), for n > 0.
T(n+1, n) = (-1)^n*A025134(n).
T(n+2, n) = (-1)^n*A025135(n).
Previous Showing 51-57 of 57 results.