This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A239315 Array read by antidiagonals: denominators of the core of the classical Bernoulli numbers. 5
 15, 15, 15, 105, 105, 105, 21, 105, 105, 21, 105, 105, 105, 105, 105, 15, 105, 105, 105, 105, 15, 165, 165, 1155, 231, 1155, 165, 165, 33, 165, 165, 231, 231, 165, 165, 33, 15015, 15015, 15015, 15015, 15015, 15015, 15015, 15015, 15015 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS We consider the autosequence A164555(n)/A027642(n) (see A190339(n)) and its difference table without the first two rows and the first two columns: 2/15,     1/15,    -1/105,   -1/21,   -1/105,     1/15,   7/165,   -5/33,... -1/15,  -8/105,    -4/105,   4/105,    8/105,   -4/165, -32/165,... -1/105,  4/105,     8/105,   4/105, -116/1155, -28/165,... 1/21,    4/105,    -4/105, -32/231,   -16/231,... -1/105, -8/105, -116/1155,  16/231,... -1/15,  -4/165,    28/165,... 7/165,  32/165,... 5/33,... etc. This is an autosequence of the second kind. The antidiagonals are palindromes in absolute values. a(n) are the denominators. Multiples of 3. Sum of odd antidiagonals: 2/15, -2/21, 2/15, -10/33, 1382/1365,... = -2*A000367(n+2)/A001897(n+2). The sum of the even antidiagonals is A000004. 2/15, 0, -2/21,... = -4*A027641(n+4)/A027642(n+4) = -4*A164555(n)/A027642(n+4) and others. LINKS EXAMPLE As a triangle: 15, 15,   15, 105, 105, 105, 21,  105, 105, 21, 105, 105, 105, 105, 105, etc. MATHEMATICA max = 12; tb = Table[BernoulliB[n], {n, 0, max}]; td = Table[Differences[tb, n][[3 ;; -1]], {n, 2, max - 1}]; Table[td[[n - k + 1, k]] // Denominator, {n, 1, max - 3}, {k, 1, n}] // Flatten (* Jean-François Alcover, Apr 11 2014 *) CROSSREFS Cf. A085737/A085738, A168516/A168426 (autosequence), A027641, A176327/A176289, A235774, A165161/A051717(n+1). Sequence in context: A225917 A140806 A085321 * A003890 A040211 A003891 Adjacent sequences:  A239312 A239313 A239314 * A239316 A239317 A239318 KEYWORD nonn,tabl,frac AUTHOR Paul Curtz, Mar 15 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 20 03:36 EDT 2019. Contains 322294 sequences. (Running on oeis4.)