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 A132120 #25 Feb 16 2025 08:33:06
%S A132120 3,6,2,3,0,6,2,2,2,3,6,6,4,9,8,0,4,8,7,9,8,6,2,6,3,7,2,2,2,4,0,9,3,4,
%T A132120 6,1,8,1,1,1,7,9,8,5,8,5,3,4,4,2,0,9,9,9,7,5,9,9,5,1,0,1,7,0,2,7,8,4,
%U A132120 1,8,8,6,3,0,6,8,9,6,5,0
%N A132120 Decimal expansion of the constant obtained through Pierce retro-expansion of the prime sequence.
%C A132120 The asymptotic density of numbers which have an odd number of the trailing zeros in their primorial base representation (A342050). - _Amiram Eldar_, Feb 28 2021
%H A132120 Paolo P. Lava, <a href="/A132120/b132120.txt">Table of n, a(n) for n = 0..1000</a>
%H A132120 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PierceExpansion.html">Pierce Expansion</a>.
%F A132120 Equals Sum_{i>=1} (-1)^(i+1)/A002110(i).
%e A132120 0.3623062223664980487986263722240934618111798585344209997599510170278418863068...
%p A132120 Digits := 80 : a := 0 : for i from 1 to 100 do a := a+(-1.0)^(i-1)/mul(ithprime(j),j=1..i) ; print(a) ; od:
%o A132120 (PARI) P=1; -sumalt(n=1,(-1)^n/P*=prime(n)) \\ _Charles R Greathouse IV_, Oct 03 2016
%Y A132120 Cf. A064648, A342050.
%K A132120 cons,nonn
%O A132120 0,1
%A A132120 _R. J. Mathar_, Oct 31 2007
%E A132120 Corrected last entry by _Paolo P. Lava_, May 28 2013