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 A111878 a(n) = A111877(n+1)/5. 1
 1, 7, 21, 231, 3003, 3003, 51051, 969969, 969969, 22309287, 111546435, 334639305, 9704539845, 300840735195, 300840735195, 300840735195, 11131107202215, 11131107202215, 456375395290815, 19624141997505045, 19624141997505045 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 FORMULA a(n) = (1/15)*denominator(digamma(n+7/2)/2 + log(2) + euler_gamma/2). a(n) = denominator(f(n+2)/15), where f(n) = Sum_{j=0..n} 1/(2*j+1). a(n) = (1/15) * denominator of ( 2*H_{2*n+6) - H_{n+3} ), where H_{n} is the n-th Harmonic number. - G. C. Greubel, Jul 24 2023 MATHEMATICA With[{H=HarmonicNumber}, Table[Denominator[2*H[2*n+6] -H[n+3]]/15, {n, 0, 40}]] (* G. C. Greubel, Jul 24 2023 *) PROG (Magma) H:=HarmonicNumber; [Denominator((2*H(2*n+6) - H(n+3)))/15: n in [0..40]]; // G. C. Greubel, Jul 24 2023 (SageMath) h=harmonic_number; [denominator(2*h(2*n+6, 1) - h(n+3, 1))/15 for n in range(41)] # G. C. Greubel, Jul 24 2023 CROSSREFS Cf. A025547, A111877. Sequence in context: A183938 A060146 A357673 * A133279 A192734 A220161 Adjacent sequences: A111875 A111876 A111877 * A111879 A111880 A111881 KEYWORD easy,nonn AUTHOR Paul Barry, Aug 19 2005 STATUS approved

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Last modified October 4 12:17 EDT 2023. Contains 365874 sequences. (Running on oeis4.)