OFFSET
1,3
LINKS
Peter Kagey, Table of n, a(n) for n = 1..10000
EXAMPLE
a(1) = 1;
a(2) = 1 because a(1) has as many or fewer divisors as 2;
a(3) = 2 because a(1) and a(2) have as many or fewer divisors as 3;
a(4) = 3 because a(1), a(2), and a(3) have as many or fewer divisors than 4;
(...)
a(7) = 5 because a(1), a(2), a(3), a(4), and a(6) have as many or fewer divisors as 7.
MATHEMATICA
a = {1}; Do[d = DivisorSigma[0, n]; AppendTo[a, Count[a, k_ /; DivisorSigma[0, k] <= d]], {n, 2, 64}]; a (* Michael De Vlieger, Feb 29 2016 *)
PROG
(Java)
int[] terms = new int[100];
terms[0] = 1;
for (int i = 1; i < 100; i++) {
int count = 0;
for (int j = 0; j < i; j++) {
if (divisors(terms[j]) <= divisors(i+1)) {
count = count + 1;
}
}
terms[i] = count;
}
(PARI) lista(nn) = {va = vector(nn); print1(va[1] = 1, ", "); for (n=2, nn, va[n] = sum(k=1, n-1, numdiv(va[k]) <= numdiv(n)); print1(va[n], ", "); ); } \\ Michel Marcus, Feb 29 2016
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Alec Jones, Feb 28 2016
STATUS
approved