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 1-3 of 3 results.

A048972 Length of record run mentioned in A048971.

Original entry on oeis.org

1, 2, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16
Offset: 1

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Author

Keywords

Examples

			54, 55, 56, 57, 58 is a run of length 5 in A001221 all with d = 2.
		

Crossrefs

Extensions

More terms from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Sep 04 2006

A048932 Let d(n) = number of distinct primes dividing n (A001221). Find smallest t such that d(t)=d(t+1)=...=d(t+n-1) but d(t-1) and d(t+n) are not = d(t); then a(n)=t.

Original entry on oeis.org

1, 14, 7, 2, 54, 91, 323, 141, 44360, 48919, 218972, 534078, 2699915, 526095, 17233173, 127890362, 29138958036, 146216247221, 118968284928, 2500769994070, 3157129230489, 22498525938216, 585927201062, 313978488186061, 571560399902283, 453918847597184
Offset: 1

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Author

Keywords

Comments

a(n) > 10^13 for n from 20 to 22. a(23) = 585927201062. - Donovan Johnson, Jul 30 2010
a(28) > 2 * 10^15. - Toshitaka Suzuki, Jun 22 2025

Examples

			a(3)=7 since 7,8,9 all have d = 1 but d(6) and d(10) != 1 and this is the first run of 3.
		

Crossrefs

First occurrence of a run of length exactly n in A001221. Cf. A048971, A048972.

Extensions

More terms from Naohiro Nomoto, Jul 13 2001
a(16)-a(19) and a(23) from Donovan Johnson, Jul 30 2010
a(20)-a(22) from Toshitaka Suzuki, Mar 24 2025
a(24)-a(27) from Toshitaka Suzuki, Jun 22 2025

A305235 Smallest positive number k such that there are exactly n successive equal values of A001221 starting at k, i.e., such that A305234(k) = n.

Original entry on oeis.org

1, 4, 3, 2, 54, 91, 142, 141, 44360, 48919, 218972, 526097, 526096, 526095, 17233173, 127890362, 29138958036, 118968284929, 118968284928, 585927201065, 585927201064, 585927201063, 585927201062, 313978488186061, 453918847597185, 453918847597184, 455626105596320
Offset: 0

Views

Author

Felix Fröhlich, May 28 2018

Keywords

Comments

a(27) > 2 * 10^15. - Toshitaka Suzuki, Jun 22 2025

Examples

			For n = 5: A001221(91+k) = 2 for k = 0..5 and 91 is the smallest number x with exactly 5 successors that have the same value of A001221 as x, so a(5) = 91.
		

Crossrefs

Programs

  • PARI
    a305234(n) = my(k=n+1, i=0); while(omega(k)==omega(n), i++; k++); i
    a(n) = my(k=1); while(1, if(a305234(k)==n, return(k)); k++)

Extensions

a(16)-a(22) from Toshitaka Suzuki, Apr 01 2025
a(23)-a(26) from Toshitaka Suzuki, Jun 22 2025
Showing 1-3 of 3 results.