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 1-2 of 2 results.

A071192 Least m>n such that the number of prime factors of m and n differ by 1.

Original entry on oeis.org

2, 4, 4, 5, 6, 7, 9, 9, 11, 11, 14, 14, 14, 17, 17, 18, 21, 21, 21, 21, 23, 23, 25, 27, 27, 27, 33, 33, 33, 33, 33, 36, 37, 37, 37, 42, 38, 41, 41, 42, 46, 46, 46, 46, 46, 47, 49, 54, 50, 51, 52, 54, 55, 63, 59, 63, 59, 59, 62, 63, 62, 63, 65
Offset: 1

Views

Author

Reinhard Zumkeller, May 15 2002

Keywords

Examples

			a(11) = 14 as 11 has one prime factor (counted with multiplicity) and 14 has 2 prime factors (counted with multiplicity) 14 the smallest number m > 11 such that the number of prime factors of m and 11 differ by 1. - _David A. Corneth_, Feb 23 2024

Links

Crossrefs

Cf. A001222, A071191, A071193.

Programs

  • PARI
    a(n) = {
	my(b = bigomega(n));
	for(i = n + 1, oo,
		if(abs(bigomega(i)-b) == 1,
			return(i)
		)
	)
} \\ David A. Corneth, Feb 23 2024
  • PARI
    a(n) = my(b=bigomega(n), k=n+1); while(abs(bigomega(k) - b) != 1, k++); k; \\ Michel Marcus, Mar 21 2025

Formula

abs(A001222(a(n)) - A001222(n)) = 1.

A071191 Least m>n such that the number of prime factors of m and n differ at most by 1.

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 9, 9, 10, 11, 13, 14, 14, 15, 17, 18, 19, 20, 21, 21, 22, 23, 25, 27, 26, 27, 28, 30, 31, 33, 33, 36, 34, 35, 37, 40, 38, 39, 41, 42, 43, 44, 46, 45, 46, 47, 49, 54, 50, 51, 52, 54, 55, 56, 57, 60, 58, 59, 61, 63, 62, 63, 65
Offset: 1

Views

Author

Reinhard Zumkeller, May 15 2002

Keywords

Comments

abs(A001222(a(n)) - A001222(n)) <= 1.

Examples

			a(11) = 13 as 11 has one prime factor (counted with multiplicity) and 13 has 1 prime factor (counted with multiplicity), 13 the smallest number m > 11 such that the number of prime factors of m and 11 differ by at most 1. - _David A. Corneth_, Feb 23 2024

Links

Crossrefs

Cf. A071192, A071193.

Programs

  • PARI
    a(n) = {
	my(b = bigomega(n));
	for(i = n + 1, oo,
		if(abs(bigomega(i)-b) <= 1,
			return(i)
		)
	)
} \\ David A. Corneth, Feb 23 2024
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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