A152986 Sum of proper divisors minus the number of proper divisors of pentagonal number A000326(n).

0, 0, 11, 11, 10, 18, 67, 71, 60, 32, 187, 351, 30, 46, 519, 337, 128, 220, 577, 483, 366, 286, 507, 1153, 248, 336, 2489, 847, 70, 818, 871, 2181, 1108, 116, 2861, 2275, 694, 130, 2763, 3645, 100, 2352, 2823, 1863, 2278, 158, 3607, 6617, 636, 920, 6181, 4019

Offset: 1

Author

Omar E. Pol, Dec 22 2008

Keywords

• easy
• nonn
• look

Links

• B. D. Swan, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000005, A000203, A000326, A001065, A032741, A152770.

Programs

Maple

A000326 := proc(n) n*(3*n-1)/2 ; end: A000203 := proc(n) numtheory[sigma](n) ; end: A000005 := proc(n) numtheory[tau](n) ; end: A152770 := proc(n) A000203(n)-A000005(n)-n+1 ; end: A152986 := proc(n) A152770(A000326(n)) ; end: for n from 1 to 80 do printf("%a,",A152986(n)) ; od: # R. J. Mathar, Jan 03 2009

Mathematica

DivisorSigma[1,#]-#-DivisorSigma[0,#]+1&/@PolygonalNumber[5,Range[60]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 02 2021 *)

Formula

a(n)=A001065(A000326(n))-A032741(A000326(n)) = A152770(A000326(n)).

Extensions

Extended by R. J. Mathar, Jan 03 2009