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Sequence of the Day

A005231: Odd abundant numbers.

{ 945, 1575, 2205, 2835, 3465, 4095, 4725, ... }
Yes, the very first abundant number to be odd is 945, the 232nd abundant number! The first abundant number is even, namely, 12.
No, the odd abundant numbers are not all divisible by 3 or 5, e.g.
 The first odd abundant number not divisible by 5 is 81081, this being the 175th odd abundant number (and the ?th abundant number).
 The first odd abundant number not divisible by 3 is 5391411025, this being the ?th odd abundant number (and the ?th abundant number).
 The first odd abundant number not divisible by neither 3 nor 5 is 20169691981106018776756331, this being the ?th odd abundant number (and the ?th abundant number).

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On this day...

Template:Today in Math History for September 23

Sequences in the news

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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