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.

User: Paul F. Marrero Romero

Paul F. Marrero Romero's wiki page.

Paul F. Marrero Romero has authored 4 sequences.

A376895 Primes of the form 3^k*k^3 + 2.

Original entry on oeis.org

2, 5, 14348909, 3502727633, 150094635296999123, 269211745384444720788843377, 2075640621314051693456929619860436129299430333182575810508680776710025092954370975575949
Offset: 1

Author

Paul F. Marrero Romero, Oct 08 2024

Keywords

Comments

A366997 are the corresponding integers k to obtain the terms of this sequence.
The next term a(8)=~2.20847*10^143 is too large to include.
The last known integer k in A366997 is 20803 and corresponds to a(13)=~3.21988*10^9938.

Crossrefs

Cf. A366997.

Programs

  • Mathematica
    Select[Table[3^k*k^3+2,{k,0,1000}],PrimeQ]

Formula

a(n) = 3^A366997(n)*A366997(n)^3 + 2.

A377045 Number of partitions of cuban primes.

Original entry on oeis.org

15, 490, 21637, 1121505, 3913864295, 1131238503938606, 78801255302666615, 5589233202595404488, 29349508915133986374841, 2163909235608484556362424, 913865816485680423486405066750, 191623400974625892978847721669762887224010
Offset: 1

Author

Paul F. Marrero Romero, Oct 14 2024

Keywords

Comments

Number of partitions of prime numbers that are the difference of two consecutive cubes.
Number of partitions of primes p such that p=(3*k^2 + 1)/4 for some integer k (A121259).

Crossrefs

Programs

  • Maple
    R:= NULL: count:= 0:
    for i from 1 while count < 30 do
      p:= (i+1)^3 - i^3;
      if isprime(p) then count:= count+1; v:= combinat:-numbpart(p); R:= R,v; fi
    od:
    R; # Robert Israel, Nov 14 2024
  • Mathematica
    PartitionsP[Select[Table[(3k^2 + 1)/4,{k,50}],PrimeQ]]

Formula

a(n) = A000041(A002407(n)).
a(n) = A000041((3*A121259(n)^2 + 1)/4).

A363743 a(n) = floor(sqrt(log_10(n!))).

Original entry on oeis.org

0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11
Offset: 0

Author

Paul F. Marrero Romero, Aug 17 2023

Keywords

Comments

Every nonnegative integer occurs at least 4 times.
Each integer k > 14 appears fewer than k times.
The only integers k that occur exactly k times are 11, 13 and 14.

Crossrefs

Programs

  • Mathematica
    Array[Floor@ Sqrt[Log10[#!]] &, 93, 0]
  • PARI
    a(n) = sqrtint(log(n!)/log(10)); \\ Michel Marcus, Sep 27 2023

Formula

a(n) = floor(sqrt(A034886(n) - 1)).
a(n) = A000196(A034886(n) - 1).

A348960 a(n) = floor(log_10(Pi*n!)).

Original entry on oeis.org

0, 0, 0, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 20, 21, 22, 24, 25, 27, 28, 29, 31, 32, 34, 35, 37, 38, 40, 42, 43, 45, 46, 48, 50, 51, 53, 54, 56, 58, 59, 61, 63, 64, 66, 68, 70, 71, 73, 75, 77, 78, 80, 82, 84, 85, 87, 89, 91, 93, 95, 96, 98, 100
Offset: 0

Author

Paul F. Marrero Romero, Nov 05 2021

Keywords

Crossrefs

Programs

Formula

a(n) = floor(log_10(Pi*n!)).
a(n) = floor(A053511 + log_10(n!)).