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%I #7 May 06 2015 21:44:14
%S 1,2,4,3,7,11,16,22,29,37,46,5,56,67,79,8,92,6,106,121,137,12,154,172,
%T 191,211,232,254,277,301,326,352,379,407,436,466,497,529,562,596,631,
%U 667,704,742,781,821,862,17,904,947,991,23,1036,1082,1129,1177,1226,1276,1327,30,1379,1432,1486,38,1541,47,1597,1654,1712,57,1771,9
%N Inverse permutation to A257503.
%H Antti Karttunen, <a href="/A257504/b257504.txt">Table of n, a(n) for n = 1..10440</a>
%H <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a>
%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%F a(n) = (1/2) * ((c+r)^2 - r - 3*c + 2), where c = A257681(n), and r = A257679(n).
%o (Scheme) (define (A257504 n) (let ((col (A257681 n)) (row (A257679 n))) (* (/ 1 2) (- (expt (+ row col) 2) row col col col -2))))
%Y Inverse: A257503.
%Y Cf. A257679, A257681.
%K nonn
%O 1,2
%A _Antti Karttunen_, May 06 2015