|
%I #7 Aug 25 2018 14:46:24
%S 1,2,4,3,16,8,256,5,9,32,65536,12,4294967296,512,64,7,
%T 18446744073709551616,18,340282366920938463463374607431768211456,48,
%U 1024,131072,115792089237316195423570985008687907853269984665640564039457584007913129639936,20,81,8589934592,25
%N Multiplicative with a(prime(i)^k) = prime(k)^2^(i-1).
%C This sequence has similarities with A048767.
%C This sequence is injective (all terms are distinct).
%C This sequence is a permutation of A268375.
%F A007947(a(n)) = A007947(A048767(n)) for any n > 0.
%F a(A005117(n)) = 2^A048672(n) for any n > 0.
%t Array[Apply[Times, FactorInteger[#] /. {p_, k_} /; p > 1 :> Prime[k]^2^(PrimePi[p] - 1)] &, 27] /. {1, 1} -> 1 (* _Michael De Vlieger_, Aug 25 2018 *)
%o (PARI) a(n) = my (f=factor(n)); prod(i=1, #f~, prime(f[i,2])^2^(primepi(f[i,1])-1))
%Y Cf. A005117, A007947, A048767, A048672, A268375.
%K nonn,mult
%O 1,2
%A _Rémy Sigrist_, Aug 24 2018
|
