This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A318363 #7 Aug 25 2018 14:46:24 %S A318363 1,2,4,3,16,8,256,5,9,32,65536,12,4294967296,512,64,7, %T A318363 18446744073709551616,18,340282366920938463463374607431768211456,48, %U A318363 1024,131072,115792089237316195423570985008687907853269984665640564039457584007913129639936,20,81,8589934592,25 %N A318363 Multiplicative with a(prime(i)^k) = prime(k)^2^(i-1). %C A318363 This sequence has similarities with A048767. %C A318363 This sequence is injective (all terms are distinct). %C A318363 This sequence is a permutation of A268375. %F A318363 A007947(a(n)) = A007947(A048767(n)) for any n > 0. %F A318363 a(A005117(n)) = 2^A048672(n) for any n > 0. %t A318363 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 A318363 (PARI) a(n) = my (f=factor(n)); prod(i=1, #f~, prime(f[i,2])^2^(primepi(f[i,1])-1)) %Y A318363 Cf. A005117, A007947, A048767, A048672, A268375. %K A318363 nonn,mult %O A318363 1,2 %A A318363 _Rémy Sigrist_, Aug 24 2018