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A245614 Permutation of natural numbers: a(1)=1; thereafter, if n is k-th number whose greatest prime factor has an odd index [i.e., n = A244991(k)], a(n) = A026424(a(k)), otherwise, when n is k-th number whose greatest prime factor has an even index [i.e., n = A244990(1+k)], a(n) = A028260(1+a(k)). 5
1, 2, 4, 3, 7, 6, 10, 5, 9, 12, 11, 16, 15, 24, 18, 8, 17, 14, 22, 20, 26, 19, 29, 25, 28, 36, 35, 55, 39, 44, 31, 13, 30, 27, 21, 38, 34, 51, 46, 42, 37, 57, 40, 47, 32, 52, 45, 62, 56, 50, 68, 60, 82, 81, 67, 121, 86, 93, 105, 72, 65, 79, 33, 59, 64, 23, 53, 48, 41, 58, 49, 85, 71, 77, 66, 111, 99 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
This shares with the permutation A122111 the property that each term of A244990 is mapped to a unique term of A028260 and each term of A244991 is mapped to a unique term of A026424.
LINKS
FORMULA
a(1) = 1, and for n > 1, if A244992(n) = 1, a(n) = A026424(a(A244989(n))), otherwise a(n) = A028260(1+a(A244988(n)-1)).
As a composition of related permutations:
a(n) = A245604(A244321(n)).
For all n >= 1, A244992(n) = A066829(a(n)).
PROG
(Scheme, with memoization macro definec)
(definec (A245614 n) (cond ((= 1 n) 1) ((= 1 (A244992 n)) (A026424 (A245614 (A244989 n)))) (else (A028260 (+ 1 (A245614 (-1+ (A244988 n))))))))
CROSSREFS
Inverse: A245613.
Sequence in context: A114537 A243349 A266413 * A246165 A260432 A021808
KEYWORD
nonn,look
AUTHOR
Antti Karttunen, Jul 27 2014
STATUS
approved

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Last modified July 19 16:24 EDT 2024. Contains 374410 sequences. (Running on oeis4.)