login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A302025 Permutation of natural numbers mapping ordinary factorization to "Ludic factorization": a(1) = 1, a(2n) = 2*a(n), a(A003961(n)) = A269379(a(n)). 9
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 23, 20, 27, 22, 25, 24, 19, 26, 21, 28, 29, 30, 37, 32, 39, 34, 35, 36, 41, 46, 63, 40, 43, 54, 47, 44, 33, 50, 53, 48, 31, 38, 75, 52, 61, 42, 65, 56, 99, 58, 67, 60, 71, 74, 57, 64, 95, 78, 77, 68, 135, 70, 83, 72, 89, 82, 51, 92, 59, 126, 91, 80, 45, 86, 97, 108, 155, 94, 147, 88 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See comments and examples in A302032 to see how Ludic factorization proceeds.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

Index entries for sequences that are permutations of the natural numbers

Index entries for sequences computed from indices in prime factorization

Index entries for sequences generated by sieves

FORMULA

a(1) = 1, a(2n) = 2*a(n), a(2n+1) = A269379(a(A064989(2n+1))).

a(n) = A269171(A250245(n)).

a(n) = A269387(A156552(n)).

PROG

(PARI)

\\ With A269379 precomputed:

A064989(n) = {my(f); f = factor(n); if((n>1 && f[1, 1]==2), f[1, 2] = 0); for (i=1, #f~, f[i, 1] = precprime(f[i, 1]-1)); factorback(f)};

A302025(n) = if(1==n, n, if(!(n%2), 2*A302025(n/2), A269379(A302025(A064989(n)))));

(Scheme, with memoization-macro definec)

(definec (A302025 n) (cond ((= 1 n) n) ((even? n) (* 2 (A302025 (/ n 2)))) (else (A269379 (A302025 (A064989 n))))))

CROSSREFS

Cf. A302026 (inverse permutation).

Cf. A156552, A250245, A269171, A269387 (similar or related permutations).

Cf. A003961, A064989, A269379.

Sequence in context: A255407 A269171 A269395 * A269396 A255408 A269172

Adjacent sequences:  A302022 A302023 A302024 * A302026 A302027 A302028

KEYWORD

nonn

AUTHOR

Antti Karttunen, Apr 03 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 9 11:08 EDT 2020. Contains 336323 sequences. (Running on oeis4.)