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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A051230 Numbers m such that the Bernoulli number B_m has denominator 66. 38
 10, 50, 170, 370, 470, 590, 610, 670, 710, 730, 790, 850, 1010, 1070, 1270, 1370, 1390, 1490, 1630, 1670, 1850, 1970, 1990, 2230, 2270, 2290, 2570, 2630, 2690, 2770, 2830, 2890, 2950, 3050, 3070, 3110, 3130, 3170, 3310, 3350, 3470, 3530 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS From the von Staudt-Clausen theorem, denominator(B_{2*m}) = product of primes p such that (p-1)|2*m. Numerator(B_m) mod denominator(B_m) = 5. - Paolo P. Lava, Mar 30 2015 REFERENCES B. C. Berndt, Ramanujan's Notebooks Part IV, Springer-Verlag, see p. 75. LINKS T. D. Noe, Table of n, a(n) for n = 1..1000 Wikipedia, Von Staudt-Clausen theorem. EXAMPLE The numbers m = 10, 50 belong to the list because B_10 = 5/66 and B_50 = 495057205241079648212477525/66. - Petros Hadjicostas, Jun 06 2020 MATHEMATICA denoBn[n_?EvenQ] := Times @@ Select[Prime /@ Range[PrimePi[n] + 1], Divisible[n, # - 1] & ]; Select[ Range[10, 4000, 10], denoBn[#] == 66 &] (* Jean-François Alcover, Jun 27 2012, after comments *) Flatten[Position[BernoulliB[Range[4000]], _?(Denominator[#]==66&)]] (* Harvey P. Dale, Nov 17 2014 *) PROG (PARI) /* define indicator function */ a(n)=local(s); s=0; fordiv(n, d, s+=isprime(d+1)&(d>2)&(d!=10)); !s /* get sequence */ an=vector(45, n, 0); m=0; forstep(n=10, 4000, 10, if(a(n), an[ m++ ]=n)); for(n=1, 42, print1(an[ n ]", ")) CROSSREFS Cf. A045979, A051222, A051225, A051226, A051227, A051228. Equals 2*A051229. Sequence in context: A196507 A008531 A337732 * A008413 A006542 A237655 Adjacent sequences:  A051227 A051228 A051229 * A051231 A051232 A051233 KEYWORD nonn,nice,easy AUTHOR EXTENSIONS More terms from Michael Somos Name edited by Petros Hadjicostas, Jun 06 2020 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 January 27 16:41 EST 2022. Contains 350611 sequences. (Running on oeis4.)