This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A061564 #27 Feb 25 2023 05:20:09 %S A061564 3,12,18,27,30,33,36,45,48,75,120,180,192,198,270,288,300,330,333,360, %T A061564 369,450,480,495,750,768,909,1152,1200,1584,1800,1875,1920,1980,1998, %U A061564 2151,2304,2439,2700,2880,2997,3000,3072,3300,3330,3333,3600,3690,4500,4800 %N A061564 Numbers k such that the repeating part of the decimal expansion of 1/k (omitting leading or trailing zeros) forms a prime number. %H A061564 <a href="/index/1#1overn">Index entries for sequences related to decimal expansion of 1/n</a> %e A061564 1/18 = 0.05555555..., the repeating part is 5, so 18 is in the sequence. %e A061564 277 is not a term because the repetend of 1/277 is 3610108303249097472924187725631768953068592057761732851985559566787, which is not a prime. - _Barry Smyth_, Mar 31 2022 %Y A061564 Cf. A036275, A060284. %K A061564 easy,nonn,base %O A061564 1,1 %A A061564 Brian Wallace (wallacebrianedward(AT)yahoo.co.uk), May 18 2001 %E A061564 Corrected and extended by _Klaus Brockhaus_, May 19 2001 %E A061564 More terms from _Lior Manor_, Nov 26 2001 %E A061564 Incorrect term 277 removed by _Barry Smyth_, Mar 31 2022 %E A061564 Corrected and extended by _Sean A. Irvine_, Feb 25 2023