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Sequence of the Day

A033879: Deficiency of .

{ ..., 14, 0, 28, −12, 30, 1, 18, ... }
The negative in this listing correspond to abundant numbers, the zeros correspond to perfect numbers and the positives correspond to deficient numbers. I'm choosing to start the listing here from in order to get a better mix of abundant, perfect and deficient numbers.

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On this day...

 December 13, 1921 Max Noether dies in Erlangen.
 December 13, 1928 Frank Ramsey reads a paper on a problem of formal logic to the London Mathematical Society.
 December 13, 1999 Neil Sloane starts a log file for the OEIS.
Sequences in the News
 Feb 01 2018 Alphabet announced a $8,589,869,056 = $A000396(6) stock buyback.
 Jan 03 2018 Largest known term of A000043 announced: 77232917.
 Nov 18 2016 PrimeGrid proves that 10223 is not a Sierpinski number, since 10223 × 2 31172165 + 1 is prime. So no changes to A076336 for now.
 Sep 14 2016 Tom Greer discovers the twin primes 2996863034895 × 2 1290000 ± 1 using PrimeGrid, TwinGen and LLR.
 Jan 19 2016 Largest known term of A000043 announced: 74207281, also discovered by Curtis Cooper.
 Mar 02 2014 Fredrik Johansson announces a computation of the partition number p(10 20) ≈ 1.8381765 × 10 11140086259, the largest known term of A000041.
 Dec 06 2013 Microsoft launches a challenge to find large nonMersenne primes, A138837.


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