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 A153825 Sum of proper divisors minus the number of proper divisors of n!. 2
 0, 0, 0, 3, 29, 225, 1669, 14245, 118705, 1118001, 11705019, 144091717, 1738439017, 24817157329, 355309322689, 5378578597729, 86081749391905, 1570394279028289, 28281459220178401, 572031558109560385, 11458497230555053681 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS a(n) is the sum of proper divisors minus the number of proper divisors of factorial number A000142(n). LINKS G. C. Greubel, Table of n, a(n) for n = 0..500 FORMULA a(n) = A153824(n) - A153823(n) = A152770(A000142(n)). MAPLE with(numtheory): seq(sigma(factorial(n))-factorial(n)-tau(factorial(n))+1, n = 0 .. 22); # Emeric Deutsch, Jan 07 2009 MATHEMATICA Table[DivisorSigma[1, n!]-n!-(DivisorSigma[0, n!]-1), {n, 0, 20}] (* Harvey P. Dale, Jan 14 2012 *) PROG (Magma) [DivisorSigma(1, Factorial(n)) - Factorial(n) - (DivisorSigma(0, Factorial(n))-1): n in [0..20]]; // Vincenzo Librandi, Aug 31 2016 (PARI) a(n) = (sigma(n!) - n!) - (numdiv(n!) - 1); \\ Michel Marcus, Aug 31 2016 CROSSREFS Cf. A000005, A000142, A000203, A001065, A032741, A062569, A152770, A153823, A153824. Sequence in context: A083092 A174419 A220548 * A201490 A354402 A135163 Adjacent sequences: A153822 A153823 A153824 * A153826 A153827 A153828 KEYWORD nonn AUTHOR Omar E. Pol, Jan 02 2009 EXTENSIONS Extended by Emeric Deutsch, Jan 07 2009 STATUS approved

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Last modified July 18 10:00 EDT 2024. Contains 374378 sequences. (Running on oeis4.)