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A152986
Sum of proper divisors minus the number of proper divisors of pentagonal number A000326(n).
1
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
1,3
FORMULA
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 *)
CROSSREFS
KEYWORD
easy,nonn,look
AUTHOR
Omar E. Pol, Dec 22 2008
EXTENSIONS
Extended by R. J. Mathar, Jan 03 2009
STATUS
approved