Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the 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