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.

A383933 Numbers k such that primorial base expansion of A276086(k) has the primorial base expansion of A003415(k) as its suffix, where A003415 is the arithmetic derivative, and A276086 is the primorial base exp-function.

Original entry on oeis.org

0, 1, 2, 6, 26, 95, 122, 185, 206, 1382, 1919, 2006, 2285, 2306, 2966, 4681, 4841, 5909, 13961, 14269, 21446, 30026, 34249, 37231, 54589, 54611, 61459, 90065, 135229, 145309, 204566, 217621, 262099, 266950, 289621, 306302, 310939, 341699, 350099, 353779, 356809, 358091, 364361, 496751, 501289, 503669, 510506, 515059
Offset: 1

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Author

Antti Karttunen, May 15 2025

Keywords

Examples

			0 and 1 are terms as A003415(0) = A003415(1) = 0, whose primorial base expansion is here understood as an empty sequence of digits, thus occurring as a suffix of all representations.
2 is a term as A003415(2) = 1, with A049345(1) = 1, which is a suffix of A049345(A276086(2)) = 11.
6 is a term as A003415(6) = 5, with A049345(5) = 21, which is a suffix of A049345(A276086(6)) = 21.
95 is a term as A003415(95) = 24, with A049345(24) = 400, which is a suffix of A049345(A276086(95)) = 272400.
		

Crossrefs

Subsequence of A383303.
Cf. also A383300.

Programs

  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    isA383933(n) = { my(p=2, k=A003415(n)); n = A276086(n); while(k, if((k%p)!=(n%p), return(0)); n = n\p; k = k\p; p = nextprime(1+p)); (1); };