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A250470 a(n) = A249817(A064989(A249818(n))).

%I A250470 #14 Dec 13 2014 00:40:23
%S A250470 1,1,2,1,3,2,5,1,4,3,7,2,11,5,6,1,13,4,17,3,8,7,19,2,9,11,10,5,23,6,
%T A250470 29,1,12,13,15,4,31,17,14,3,37,10,41,7,16,19,43,2,25,9,18,11,47,8,21,
%U A250470 5,20,23,53,6,59,29,22,1,27,14,61,13,24,15,67,4,71,31,26,17,35,22,73,3,28,37,79,10,33,41,30,7,83,12,55,19,32,43,39,2,89,25,34,9,97,26,101
%N A250470 a(n) = A249817(A064989(A249818(n))).
%C A250470 Odd bisection, A250472, is a permutation of natural numbers. A250479 gives the even bisection.
%C A250470 For odd numbers n >= 3, a(n) = A078898(n)-th number k for which A055396(k) = A055396(n)-1. In other words, a(n) tells which number is located immediately above n in the sieve of Eratosthenes (see A083140, A083221) in the same column of the sieve that contains n.
%H A250470 Antti Karttunen, <a href="/A250470/b250470.txt">Table of n, a(n) for n = 1..9048</a>
%F A250470 a(n) = A249817(A064989(A249818(n))).
%F A250470 Other identities. For all n >= 1:
%F A250470 a(A250469(n)) = n. [This is an inverse function for injection A250469.]
%F A250470 For all odd numbers n >= 3: A055396(a(n)) = A055396(n)-1.
%o A250470 (Scheme) (define (A250470 n) (A249817 (A064989 (A249818 n))))
%Y A250470 Cf. A055396, A064989, A078898, A083140, A083221, A249744, A249810, A249820, A249817, A249818, A250469.
%Y A250470 Odd bisection: A250472.
%Y A250470 Even bisection: A250479.
%Y A250470 Differs from A064989 for the first time at n=21, where a(21) = 8, while
%Y A250470 A064989(21) = 10.
%K A250470 nonn
%O A250470 1,3
%A A250470 _Antti Karttunen_, Dec 06 2014