@prefix psr: . @prefix skos: . @prefix dc: . @prefix xsd: . psr: a skos:ConceptScheme . psr:-NHFK3Q1R-H skos:prefLabel "fonction L"@fr, "L-function"@en ; a skos:Concept ; skos:narrower psr:-X5ZGR7J4-2 . psr:-X5ZGR7J4-2 skos:definition """In mathematics, the Feller–Tornier constant C_FT is the density of the set of all positive integers that have an even number of distinct prime factors raised to a power larger than one (ignoring any prime factors which appear only to the first power). It is named after William Feller (1906–1970) and Erhard Tornier (1894–1982)

{\\\\displaystyle {\\egin{aligned}C_{\\ ext{FT}}&={1 \\\\over 2}+\\\\left({1 \\\\over 2}\\\\prod _{n=1}^{\\\\infty }\\\\left(1-{2 \\\\over p_{n}^{2}}\\ ight)\\ ight)\\\\\\\\&={{1} \\\\over {2}}\\\\left(1+\\\\prod _{n=1}^{\\\\infty }\\\\left(1-{{2} \\\\over {p_{n}^{2}}}\\ ight)\\ ight)\\\\\\\\&={1 \\\\over 2}\\\\left(1+{{1} \\\\over {\\\\zeta (2)}}\\\\prod _{n=1}^{\\\\infty }\\\\left(1-{{1} \\\\over {p_{n}^{2}-1}}\\ ight)\\ ight)\\\\\\\\&={1 \\\\over 2}+{{3} \\\\over {\\\\pi ^{2}}}\\\\prod _{n=1}^{\\\\infty }\\\\left(1-{{1} \\\\over {p_{n}^{2}-1}}\\ ight)=0.66131704946\\\\ldots \\\\end{aligned}}}

(sequence A065493 in the OEIS)
(Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/wiki/Feller%E2%80%93Tornier_constant)"""@en ; a skos:Concept ; skos:prefLabel "Feller-Tornier constant"@en, "constante de Feller-Tornier"@fr ; dc:created "2023-08-21"^^xsd:date ; skos:exactMatch ; skos:broader psr:-NHFK3Q1R-H, psr:-RBFVN7DN-2 ; skos:inScheme psr: ; dc:modified "2024-10-18"^^xsd:date . psr:-RBFVN7DN-2 skos:prefLabel "mathematical constant"@en, "constante mathématique"@fr ; a skos:Concept ; skos:narrower psr:-X5ZGR7J4-2 .