OFFSET
2,1
COMMENTS
Contains no primes except for a(2)=3. Contains every number of the form p+1 for prime p (that is, every element of A008864). Contains no powers of 2 except those one more than a Mersenne prime.
LINKS
Robert Israel, Table of n, a(n) for n = 2..10000
EXAMPLE
For n=2, a(n) = 2+1 = 3.
For n=6, a(n) = 6+3 = 9.
MAPLE
f:= n -> n *(1+1/min(numtheory:-factorset(n))):
map(f, [$2..100]); # Robert Israel, Oct 28 2020
MATHEMATICA
a[n_] := n + n/FactorInteger[n][[1, 1]]; Array[a, 100, 2] (* Amiram Eldar, Oct 21 2020 *)
PROG
(Python)
def a(n):
if(n<4):
return 1+n
i=2
while (n%i!=0):
if i*i>n:
return 1+n
i+=1
return (n//i)+n
CROSSREFS
KEYWORD
nonn
AUTHOR
Allen G. Liu, Oct 21 2020
STATUS
approved