A252460 - OEIS

%I #11 Dec 23 2014 00:35:58

%S 1,2,4,3,7,5,11,8,6,12,16,17,22,23,9,30,29,38,37,47,13,57,46,68,10,80,

%T 18,93,56,107,67,122,24,138,14,155,79,173,31,192,92,212,106,233,39,

%U 255,121,278,15,302,48,327,137,353,19,380,58,408,154,437,172,467,69,498,25,530,191,563,81,597,211,632,232,668,94,705,20

%N Inverse permutation to A083221 considered as a permutation of natural numbers (with assumption that a(1) = 1).

%H Antti Karttunen, <a href="/A252460/b252460.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>

%F a(1) = 1; for n>1: a(n) = 2 + ((((x+y)^2) - x - 3*y)/2), where x = A055396(n) and y = A078898(n).

%F a(1) = 1; for n>1: a(n) = 1 + A249742(n-1).

%o (Scheme. Two variants)

%o (define (A252460 n) (if (<= n 1) n (let ((x (A055396 n)) (y (A078898 n))) (+ 1 (* (/ 1 2) (- (expt (+ x y) 2) x y y y -2))))))

%o (define (A252460 n) (if (<= n 1) n (+ 1 (A249742 (- n 1)))))

%Y Essentially after a(1) one more than A249742.

%Y Inverse permutation: A083221.

%Y Cf. A055396, A078898.

%K nonn,look

%O 1,2

%A _Antti Karttunen_, Dec 19 2014