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 A283478 #12 May 15 2017 19:56:22 %S A283478 1,2,6,3,30,5,210,6,15,7,2310,10,30030,11,21,5,510510,30,9699690,14, %T A283478 33,13,223092870,15,105,17,14,22,6469693230,42,200560490130,10,39,19, %U A283478 165,7,7420738134810,23,51,21,304250263527210,66,13082761331670030,26,70,29,614889782588491410,30,1155,210,57,34,32589158477190044730,21,195,33,69,31 %N A283478 a(n) = A097248(A108951(n)). %H A283478 Antti Karttunen, <a href="/A283478/b283478.txt">Table of n, a(n) for n = 1..1024</a> %F A283478 a(n) = A097248(A108951(n)). %F A283478 Other identities: %F A283478 For all n >= 0, a(A019565(n)) = A283475(n). %t A283478 Table[FixedPoint[Times @@ Map[#1^#2 & @@ # &, Partition[#, 2, 2] &@ Flatten[FactorInteger[#] /. {p_, e_} /; e >= 2 :> {If[OddQ@ e, {p, 1}, {1, 1}], {NextPrime@ p, Floor[e/2]}}]] &, #] &[Times @@ Map[#1^#2 & @@ # &, FactorInteger[n] /. {p_, e_} /; e > 0 :> {Times @@ Prime@ Range@ PrimePi@ p, e}]], {n, 58}] (* _Michael De Vlieger_, Mar 18 2017 *) %o A283478 (PARI) %o A283478 A034386(n) = prod(i=1, primepi(n), prime(i)); %o A283478 A108951(n) = { my(f=factor(n)); prod(i=1, #f~, A034386(f[i, 1])^f[i, 2]) }; \\ From _Charles R Greathouse IV_, Jun 28 2015 %o A283478 A097246(n) = { my(f=factor(n)); prod(i=1, #f~, (nextprime(f[i,1]+1)^(f[i,2]\2))*((f[i,1])^(f[i,2]%2))); }; %o A283478 A097248(n) = { my(k=A097246(n)); while(k<>n, n = k; k = A097246(k)); k; }; %o A283478 A283478(n) = A097248(A108951(n)); %o A283478 (Scheme) (define (A283478 n) (A097248 (A108951 n))) %o A283478 (Python) %o A283478 from sympy import primerange, factorint, nextprime %o A283478 from operator import mul %o A283478 def P(n): return reduce(mul, [i for i in primerange(2, n + 1)]) %o A283478 def a108951(n): %o A283478 f = factorint(n) %o A283478 return 1 if n==1 else reduce(mul, [P(i)**f[i] for i in f]) %o A283478 def a097246(n): %o A283478 f=factorint(n) %o A283478 return 1 if n==1 else reduce(mul, [(nextprime(i)**int(f[i]/2))*(i**(f[i]%2)) for i in f]) %o A283478 def a097248(n): %o A283478 k=a097246(n) %o A283478 while k!=n: %o A283478 n=k %o A283478 k=a097246(k) %o A283478 return k %o A283478 def a(n): return a097248(a108951(n)) # _Indranil Ghosh_, May 15 2017 %Y A283478 Cf. A019565, A097248, A108951, A283475. %K A283478 nonn %O A283478 1,2 %A A283478 _Antti Karttunen_, Mar 16 2017