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A302849 Permutation of natural numbers: a(1) = 1, a(2) = 2; for n > 2, a(n) = A064989(4+A003961(n-2)).

%I A302849 #5 Apr 26 2018 17:43:14
%S A302849 1,2,3,5,4,11,7,17,6,29,23,9,13,25,10,31,22,39,19,73,8,61,53,41,14,
%T A302849 137,47,21,82,101,15,107,37,187,38,59,16,227,12,71,83,191,43,121,26,
%U A302849 49,173,55,34,401,27,149,28,151,20,373,51,205,65,89,33,161,67,57,116,727,74,197,18,45,139,129,35,445,79,113,158,199,50,155,46,569,403,85,58
%N A302849 Permutation of natural numbers: a(1) = 1, a(2) = 2; for n > 2, a(n) = A064989(4+A003961(n-2)).
%H A302849 Antti Karttunen, <a href="/A302849/b302849.txt">Table of n, a(n) for n = 1..20000</a>
%H A302849 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%H A302849 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%F A302849 a(1) = 1, a(2) = 2; for n > 2, a(n) = A064989(4+A003961(n-2)).
%o A302849 (PARI)
%o A302849 A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ From A003961
%o A302849 A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
%o A302849 A302849(n) = if(n<=2,n,A064989(4+A003961(n-2)));
%Y A302849 Cf. A302850 (inverse).
%Y A302849 Cf. A003961, A064989, A302847.
%K A302849 nonn
%O A302849 1,2
%A A302849 _Antti Karttunen_, Apr 26 2018