OFFSET
1,2
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..16384
EXAMPLE
The number of divisors of the integers 1 through 10 form the sequence 1,2,2,3,2,4,2,4,3,4. The divisors of 10 are 1,2,5,10. The divisors of 10 which occur in the sequence of d(k)'s, 1<=k<=10, are 1 and 2. So a(10) = 1+2 = 3.
MATHEMATICA
f[n_] :=Plus @@ Select[Divisors[n], MemberQ[Table[Length@Divisors[k], {k, n}], # ] &]; Table[f[n], {n, 91}] (* Ray Chandler, Dec 21 2006 *)
PROG
(PARI) A126212(n) = sumdiv(n, d, my(s=0); for(k=1, n, if(numdiv(k)==d, s++; break)); (d*s)); \\ Antti Karttunen, Apr 01 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Dec 20 2006
EXTENSIONS
Extended by Ray Chandler, Dec 21 2006
STATUS
approved