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 1-6 of 6 results.

A248132 Integer part of square root of A010813(n) = n^25.

Original entry on oeis.org

0, 1, 5792, 920482, 33554432, 545915033, 5332006004, 36620603758, 194368031998, 847288609443, 3162277660168, 10408989356987, 30886277963534, 84002440529229, 212129196024140, 502505405881790, 1125899906842624
Offset: 0

Views

Author

Karl V. Keller, Jr., Oct 02 2014

Keywords

Examples

			For n = 4, floor(sqrt(n^25)) = 33554432.
		

Crossrefs

Cf. A010813 (n^25).

Programs

  • Mathematica
    Table[Floor[Sqrt[n^25]],{n,0,20}] (* Harvey P. Dale, Aug 27 2017 *)
  • Python
    from math import isqrt
    print([isqrt(n**25) for n in range(0, 21)])

Formula

a(n) = floor(sqrt(n^25)).

A003992 Square array read by upwards antidiagonals: T(n,k) = n^k for n >= 0, k >= 0.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 4, 1, 0, 1, 4, 9, 8, 1, 0, 1, 5, 16, 27, 16, 1, 0, 1, 6, 25, 64, 81, 32, 1, 0, 1, 7, 36, 125, 256, 243, 64, 1, 0, 1, 8, 49, 216, 625, 1024, 729, 128, 1, 0, 1, 9, 64, 343, 1296, 3125, 4096, 2187, 256, 1, 0, 1, 10, 81, 512, 2401, 7776, 15625, 16384, 6561, 512, 1, 0
Offset: 0

Views

Author

Keywords

Comments

If the array is transposed, T(n,k) is the number of oriented rows of n colors using up to k different colors. The formula would be T(n,k) = [n==0] + [n>0]*k^n. The generating function for column k would be 1/(1-k*x). For T(3,2)=8, the rows are AAA, AAB, ABA, ABB, BAA, BAB, BBA, and BBB. - Robert A. Russell, Nov 08 2018
T(n,k) is the number of multichains of length n from {} to [k] in the Boolean lattice B_k. - Geoffrey Critzer, Apr 03 2020

Examples

			Rows begin:
[1, 0,  0,   0,    0,     0,      0,      0, ...],
[1, 1,  1,   1,    1,     1,      1,      1, ...],
[1, 2,  4,   8,   16,    32,     64,    128, ...],
[1, 3,  9,  27,   81,   243,    729,   2187, ...],
[1, 4, 16,  64,  256,  1024,   4096,  16384, ...],
[1, 5, 25, 125,  625,  3125,  15625,  78125, ...],
[1, 6, 36, 216, 1296,  7776,  46656, 279936, ...],
[1, 7, 49, 343, 2401, 16807, 117649, 823543, ...], ...
		

Crossrefs

Main diagonal is A000312. Other diagonals include A000169, A007778, A000272, A008788. Antidiagonal sums are in A026898.
Cf. A099555.
Transpose is A004248. See A051128, A095884, A009999 for other versions.
Cf. A277504 (unoriented), A293500 (chiral).

Programs

  • Magma
    [[(n-k)^k: k in [0..n]]: n in [0..10]]; // G. C. Greubel, Nov 08 2018
  • Mathematica
    Table[If[k == 0, 1, (n - k)^k], {n, 0, 11}, {k, 0, n}]//Flatten
  • PARI
    T(n,k) = (n-k)^k \\ Charles R Greathouse IV, Feb 07 2017
    

Formula

E.g.f.: Sum T(n,k)*x^n*y^k/k! = 1/(1-x*exp(y)). - Paul D. Hanna, Oct 22 2004
E.g.f.: Sum T(n,k)*x^n/n!*y^k/k! = e^(x*e^y). - Franklin T. Adams-Watters, Jun 23 2006

Extensions

More terms from David W. Wilson
Edited by Paul D. Hanna, Oct 22 2004

A089081 26th powers: a(n) = n^26.

Original entry on oeis.org

0, 1, 67108864, 2541865828329, 4503599627370496, 1490116119384765625, 170581728179578208256, 9387480337647754305649, 302231454903657293676544, 6461081889226673298932241, 100000000000000000000000000
Offset: 0

Views

Author

Douglas Winston (douglas.winston(AT)srupc.com), Dec 04 2003

Keywords

Crossrefs

Programs

Formula

a(n) = n^26.
Completely multiplicative sequence with a(p) = p^26 for prime p. Multiplicative sequence with a(p^e) = p^(26e). - Jaroslav Krizek, Nov 01 2009
From Amiram Eldar, Oct 09 2020: (Start)
Dirichlet g.f.: zeta(s-26).
Sum_{n>=1} 1/a(n) = zeta(26) = 1315862*Pi^26/11094481976030578125.
Sum_{n>=1} (-1)^(n+1)/a(n) = 33554431*zeta(26)/33554432 = 22076500342261*Pi^26/186134520519971831808000000. (End)

A122968 27th powers: a(n) = n^27.

Original entry on oeis.org

0, 1, 134217728, 7625597484987, 18014398509481984, 7450580596923828125, 1023490369077469249536, 65712362363534280139543, 2417851639229258349412352, 58149737003040059690390169
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

Formula

Totally multiplicative sequence with a(p) = p^27 for prime p. Multiplicative sequence with a(p^e) = p^(27e). - Jaroslav Krizek, Nov 01 2009
From Amiram Eldar, Oct 09 2020: (Start)
Dirichlet g.f.: zeta(s-27).
Sum_{n>=1} 1/a(n) = zeta(27).
Sum_{n>=1} (-1)^(n+1)/a(n) = 67108863*zeta(27)/67108864. (End)

A122969 28th powers: a(n) = n^28.

Original entry on oeis.org

0, 1, 268435456, 22876792454961, 72057594037927936, 37252902984619140625, 6140942214464815497216, 459986536544739960976801, 19342813113834066795298816, 523347633027360537213511521
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

Formula

Totally multiplicative sequence with a(p) = p^28 for prime p. Multiplicative sequence with a(p^e) = p^(28e). - Jaroslav Krizek, Nov 01 2009
From Amiram Eldar, Oct 09 2020: (Start)
Dirichlet g.f.: zeta(s-28).
Sum_{n>=1} 1/a(n) = zeta(28) = 6785560294*Pi^28/564653660170076273671875.
Sum_{n>=1} (-1)^(n+1)/a(n) = 134217727*zeta(28)/134217728 = 65053034220152267*Pi^28/5413323669636552217067520000000. (End)

A137489 Numbers with 26 divisors.

Original entry on oeis.org

12288, 20480, 28672, 45056, 53248, 69632, 77824, 94208, 118784, 126976, 151552, 167936, 176128, 192512, 217088, 241664, 249856, 274432, 290816, 299008, 323584, 339968, 364544, 397312, 413696, 421888, 438272, 446464, 462848, 520192, 536576
Offset: 1

Views

Author

R. J. Mathar, Apr 22 2008

Keywords

Comments

Maple implementation: see A030513.
Numbers of the form p^25 (5th powers of A050997, subset of A010813) or p*q^12, where p and q are distinct primes. - R. J. Mathar, Mar 01 2010

Crossrefs

Programs

Formula

A000005(a(n))=26.
Showing 1-6 of 6 results.