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 A186720 As p runs through the primes, sequence gives denominator of Sum_{k=1..p-1} 1/k^2. 2
 1, 4, 144, 3600, 1270080, 153679680, 519437318400, 150117385017600, 221193371393280, 6450247552370862240000, 5424658191543895143840000, 20852386088294732932920960000, 28546916554875489385168794240000, 6855338104106528236638391873920000, 12675520154492970709544386574878080000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS R. Mestrovic, Wolstenholme's theorem: Its Generalizations and Extensions in the last hundred and fifty years (1862-2011), arXiv:1111.3057 [math.NT], 2011. MAPLE f2:=proc(n) local p; p:=ithprime(n); denom(add(1/i^2, i=1..p-1)); end proc; [seq(f2(n), n=1..20)]; MATHEMATICA a[n_] := HarmonicNumber[Prime[n] - 1, 2] // Denominator; Array[a, 15] (* Jean-François Alcover, Nov 25 2017 *) CROSSREFS Cf. A125551, A061002. Sequence in context: A134631 A036511 A263386 * A060870 A268894 A084703 Adjacent sequences:  A186717 A186718 A186719 * A186721 A186722 A186723 KEYWORD nonn AUTHOR N. J. A. Sloane, Jan 21 2012 STATUS approved

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Last modified September 27 17:05 EDT 2021. Contains 347693 sequences. (Running on oeis4.)