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A051230
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Bernoulli number B_{n} has denominator 66.
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10
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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
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OFFSET
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1,1
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COMMENTS
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From the Von Staudt-Clausen theorem, denominator(B_2n) = product of primes p such that (p-1)|2n.
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REFERENCES
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B. C. Berndt, Ramanujan's Notebooks Part IV, Springer-Verlag, see p. 75.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
Index entries for sequences related to Bernoulli numbers.
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MATHEMATICA
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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 *)
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PROG
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(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 ]", "))
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CROSSREFS
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Cf. A045979, A051222, A051225-A051229. Equals 2*A051229.
Sequence in context: A153780 A196507 A008531 * A008413 A006542 A086462
Adjacent sequences: A051227 A051228 A051229 * A051231 A051232 A051233
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KEYWORD
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nonn,nice,easy
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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More terms from Michael Somos.
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STATUS
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approved
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