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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 non-Mersenne primes, A138837.


Sequence of the Day

Sequence of the Day for September 19

A003188: Decimal equivalent of Gray code for
n
.
{0, 1, 3, 2, 6, 7, 5, 4, 12, 13, 15, 14, 10, 11, 9, 8, 24, 25, 27, 26, 30, 31, 29, ... }
In binary, visits every node of an
n
-cube, by a change of exactly one coordinate (
0
to
1
or
1
to
0
).
     
a (n) = n XOR
n
2
.
a (0) = 0; a (n) = 2 a
  
n
2
+
n + 1
2
mod 2, n ≥ 1.

Selected Recent Additions

  • A239797 Decimal expansion of .
  • A238271 Decimal expansion of .
  • A237042 UPC check digits.
  • A236603 Lowest canonical Gray cycles of length .
  • A235365 Smallest odd prime factor of .
  • A234522 Decimal expansion of .
  • A233748 Number of graphs on n vertices with edges colored with at most four interchangeable colors under the symmetries of the full edge permutation group.
  • A232499 Number of unit squares, aligned with a Cartesian grid, completely within the first quadrant of a circle centered at the origin ordered by increasing radius.
  • A231963 Concatenate with its UPC check digit.
  • A230624 Numbers with property that for every base , there is a number such that , where is the sum of digits in the base expansion of .


Today in Math History

Today in Math History for September 19

  • September 19, 1994 Andrew Wiles realizes that the horizontal Iwasawa theory is the way to correct his proof of Fermat's conjecture.

It remains unclear at this point whether the accident would have been prevented if existing measures had been enforced. The incident was in some ways different from what the legislators intended to prevent when many of these measures were signed into law twenty years ago. A subcommittee has been appointed to review possible unintended consequences of tougher measures.

Since the classifying authority also classified the reason the requested information was classified in the first place, the judge had no choice but to dismiss all charges, though without prejudice. The prosecutor, however, remains convinced that other evidence will soon come to light which will enable her to refile all charges.

The filibuster was averted at the last minute when a small group of legislators decided to ignore their party's position on the issue and side with the majority. The vote was nevertheless very close and mostly along party lines. The president has not given any indication on whether he will sign or veto the bill now that those provisions he declared most important at the outset have been significantly weakened.

TeX Tests

The function for counts how many prime numbers there are between 0 and .

  • A184336:

Table Test

Cell 1 Cell 2
Cell 3
Cell 4 Cell 5

After much deliberation, the panel decided to postpone further discussion of the issue until more information becomes available. In the meantime, the investigation will proceed, but at a lower priority level. The panel also recommended that the chain of custody be strictly observed and documented until further notice.

“I don't know what I would have done if that had been the case,” John Smith said at the press conference convened earlier today. “At the time, I was operating under the assumption that all the prototypes were back in hangar,” he explained. Later on it was learned that one of the prototypes was still unaccounted for, though it was retrieved prior to the press conference.

General consensus has it that the subcommittee's meeting with the provost was designed not so much to change his mind as to delineate which points were open to concession and which were not. With both parties to the dispute digging in their heels, it appears that a resolution of the disagreement is not forthcoming at any point in the near future.

It remains unclear at this point whether the accident would have been prevented if existing measures had been enforced. The incident was in some ways different from what the legislators intended to prevent when many of these measures were signed into law twenty years ago. A subcommittee has been appointed to review possible unintended consequences of tougher measures.

The vote was nevertheless very close and mostly along party lines. The president has not given any indication on whether he will sign or veto the bill now that those provisions he declared most important at the outset have been significantly weakened.