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.

A141404 Irregular array: For any prime p that divides n, if the highest power of the prime p that divides n is p^b(n,p), then p^b(n,p) = Sum_{k=1..m} a(n,k), where m is the order of the prime-power p^b(n,p) among the prime-powers (each being the highest power of each prime q that divides n, where q divides n) when they are ordered by size. Row 1 = (1).

Original entry on oeis.org

1, 2, 3, 4, 5, 2, 1, 7, 8, 9, 2, 3, 11, 3, 1, 13, 2, 5, 3, 2, 16, 17, 2, 7, 19, 4, 1, 3, 4, 2, 9, 23, 3, 5, 25, 2, 11, 27, 4, 3, 29, 2, 1, 2, 31, 32, 3, 8, 2, 15, 5, 2, 4, 5, 37, 2, 17, 3, 10, 5, 3, 41, 2, 1, 4, 43, 4, 7, 5, 4, 2, 21, 47, 3, 13, 49, 2, 23, 3, 14, 4, 9, 53, 2, 25, 5, 6, 7, 1, 3, 16, 2
Offset: 1

Views

Author

Leroy Quet, Aug 03 2008

Keywords

Comments

Row n contains A001221(n) terms.

Examples

			The prime factorization of 300 is 2^2 *3^1 *5^2. So the prime powers ordered by size are 3, 4, 25. Therefore row 300 is (3,1,21), because 3=3, 3+1 = 4, 3+1+21 = 25.
		

Crossrefs

Programs

  • PARI
    { A141404row(n) = my(f); if(n==1,return([1])); f=factorint(n); f=vecsort(vector(matsize(f)[1],i,f[i,1]^f[i,2])); vector(#f,i,f[i]-if(i>1,f[i-1])); } \\ Max Alekseyev, May 07 2009

Extensions

Extended by Max Alekseyev, May 07 2009