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A249742 Inverse permutation to A249741. 5
1, 3, 2, 6, 4, 10, 7, 5, 11, 15, 16, 21, 22, 8, 29, 28, 37, 36, 46, 12, 56, 45, 67, 9, 79, 17, 92, 55, 106, 66, 121, 23, 137, 13, 154, 78, 172, 30, 191, 91, 211, 105, 232, 38, 254, 120, 277, 14, 301, 47, 326, 136, 352, 18, 379, 57, 407, 153, 436, 171, 466, 68, 497, 24, 529, 190, 562, 80, 596, 210, 631, 231, 667, 93, 704, 19 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..8192
Index entries for sequences that are permutations of the natural numbers
FORMULA
a(n) = 1 + ((((x+y)^2) - x - 3*y)/2), where x = A055396(n+1) and y = A078898(n+1).
As a composition of related permutations:
a(n) = A249725(A249812(n)).
Other identities.
For all n >= 0 the following holds:
a(A005408(n)) = A000124(n). [Maps odd numbers to central polygonal numbers.]
For all n >= 1 the following holds:
a(A006093(n)) = A000217(n). [Maps precedents of primes to triangular numbers.]
PROG
(Scheme) (define (A249742 n) (let ((x (A055396 (+ 1 n))) (y (A078898 (+ 1 n)))) (* (/ 1 2) (- (expt (+ x y) 2) x y y y -2))))
CROSSREFS
Inverse: A249741.
Cf. A000124, A000217, A005408, A006093, A055396, A078898.
Similar or related permutations: A249725, A249812, A250252.
Differs from A246276 for the first time at n=20, where a(20) = 12, while A246276(20) = 17.
Sequence in context: A094077 A375113 A260220 * A246276 A091018 A248971
Adjacent sequences: A249739 A249740 A249741 * A249743 A249744 A249745
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 15 2014
STATUS
approved

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Last modified August 18 15:24 EDT 2024. Contains 375269 sequences. (Running on oeis4.)