A091195 Number of numbers <= n having only one abundant divisor (A091191).

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10

Offset: 1

Author

Reinhard Zumkeller, Dec 27 2003

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Abundant Number.

Crossrefs

Partial sums of A294930.

Cf. A091191, A091194, A005101.

Programs

Mathematica

f[n_] := Boole[Count[Divisors[n], ?(DivisorSigma[1, #] > 2 # &)] == 1]; Accumulate @ Array[f, 100] (* _Amiram Eldar, Mar 21 2021 *)