The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A073806 Number of divisors of sum of square of divisors. 1
 1, 2, 4, 4, 4, 6, 6, 4, 4, 8, 4, 16, 8, 8, 12, 4, 8, 8, 4, 16, 12, 8, 8, 12, 8, 12, 12, 24, 4, 18, 8, 16, 12, 12, 18, 12, 8, 8, 18, 16, 6, 15, 12, 16, 12, 12, 16, 16, 8, 16, 18, 32, 8, 18, 12, 16, 12, 8, 4, 48, 4, 16, 24, 4, 24, 18, 8, 32, 18, 24, 4, 16, 16, 12, 32, 16, 18, 24, 4, 16, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A000005(A001157(n)) = d(sigma(2, n)). EXAMPLE n = 10: D = {1,2,5,10}, sigma(2,10) = 1 + 4 + 25 + 100 = 130, D(130) = {1,2,5,10,13,26,65,130}, so a(10) = 8. MATHEMATICA a[n_] := DivisorSigma[0, DivisorSigma[2, n]]; Array[a, 81] (* Amiram Eldar, Aug 01 2019 *) CROSSREFS Cf. A000005, A000203, A001157, A062068, A073802-A073813. Sequence in context: A084291 A258573 A060271 * A060849 A130819 A307097 Adjacent sequences: A073803 A073804 A073805 * A073807 A073808 A073809 KEYWORD nonn AUTHOR Labos Elemer, Aug 13 2002 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified February 4 02:26 EST 2023. Contains 360045 sequences. (Running on oeis4.)