A338362 Inverse permutation to A283312.
1, 2, 4, 3, 6, 5, 8, 10, 11, 7, 12, 14, 15, 9, 17, 18, 19, 21, 22, 24, 25, 13, 26, 28, 29, 16, 30, 31, 32, 34, 35, 37, 38, 20, 39, 40, 41, 23, 43, 44, 45, 47, 48, 50, 51, 27, 52, 54, 55, 56, 57, 58, 59, 61, 62, 63, 64, 33, 65, 67, 68, 36, 70, 71, 72, 73, 74, 76, 77, 78, 79, 81, 82
Offset: 1
Keywords
Links
- N. J. A. Sloane, Table of n, a(n) for n = 1..10000
Programs
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Maple
g := m -> m+pi(m)-pi(m/2); # A338363 A338362 := proc(n) global g; if isprime(n) then return(g(n)-1); fi; if type(n,even) then if isprime(n/2) then return(g(n/2)); fi; fi; return(g(n)); end proc; [seq(A338362(n),n=1..128)];
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Mathematica
g[n_] := n + PrimePi[n] - PrimePi[n/2]; a[n_] := Which[PrimeQ[n], g[n]-1, PrimeQ[n/2], g[n/2], True, g[n]]; Table[a[n], {n, 1, 128}] (* Jean-François Alcover, Apr 04 2023 *)