The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A187745 Numerators of Bernoulli numbers B(2^n). 0
 1, 1, 1, -1, -1, -3617, -7709321041217, -106783830147866529886385444979142647942017 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,6 COMMENTS Interestingly, the terms |a(n)| mod 100 show some regularity : 1, 1, 1, 1, 1, 17, 17, 17, 17, 69, 69, 69, 69, 69, 69, 69, 69, 53, 53, 53, 53, 53, ... The only prime term up to a(20) is a(5) LINKS Table of n, a(n) for n=0..7. FORMULA a(n) = A164555(A131577(n)) MATHEMATICA A164555[n_] := If[n <= 2, 1, BernoulliB[n] // Numerator]; A131577[n_] := If[n == 0, 0, 2^(n-1)]; a[n_] := A164555[A131577[n]]; (* or *) a[n_] := n!*Coefficient[ Series[x/(1-Exp[-x]), {x, 0, 2^6}], x, Max[1, 2^(n-1)]] // Numerator; Table[a[n], {n, 0, 7}] PROG (Magma) A164555:=func; [A164555(2^(n-1)): n in [0..10]]; // Bruno Berselli, Jan 09 2013 CROSSREFS Sequence in context: A188309 A185495 A029829 * A329539 A329540 A223414 Adjacent sequences: A187742 A187743 A187744 * A187746 A187747 A187748 KEYWORD sign,frac AUTHOR Jean-François Alcover, Jan 03 2013 STATUS approved

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

Last modified June 19 13:19 EDT 2024. Contains 373503 sequences. (Running on oeis4.)