cp's OEIS Frontend

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.

A364258 a(n) = A163511(n) - n.

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%I A364258 #23 Jul 26 2023 14:32:59
%S A364258 1,1,2,0,4,4,0,-2,8,18,8,14,0,2,-4,-8,16,64,36,106,16,54,28,26,0,20,4,
%T A364258 8,-8,-8,-16,-20,32,210,128,590,72,338,212,304,32,184,108,202,56,102,
%U A364258 52,74,0,86,40,124,8,52,16,22,-16,6,-16,-4,-32,-28,-40,-50,64,664,420,3058,256,1806,1180,2330,144,1052,676
%N A364258 a(n) = A163511(n) - n.
%C A364258 Compare also to the scatter plot of A364294.
%H A364258 Antti Karttunen, <a href="/A364258/b364258.txt">Table of n, a(n) for n = 0..12288</a>
%F A364258 a(n) = A364288(A163511(n)).
%F A364258 For n >= 1, a(2*n) = 2*a(n).
%F A364258 For n >= 0, a(A007283(n)) = 0.
%t A364258 f[n_] := Reverse@ Map[Ceiling[(Length@ # - 1)/2] &, DeleteCases[Split@ Join[Riffle[IntegerDigits[n, 2], 0], {0}], {k__} /; k == 1]]; {1}~Join~Table[-n + Function[t, Prime[t] Product[Prime[m]^(f[n][[m]]), {m, t}] ][DigitCount[n, 2, 1]], {n, 120}] (* _Michael De Vlieger_, Jul 25 2023 *)
%o A364258 (Python)
%o A364258 from sympy import nextprime
%o A364258 def A364258(n):
%o A364258     c, p, k = 1, 1, n
%o A364258     while k:
%o A364258         c *= (p:=nextprime(p))**(s:=(~k&k-1).bit_length())
%o A364258         k >>= s+1
%o A364258     return c*p-n # _Chai Wah Wu_, Jul 25 2023
%Y A364258 Cf. A007283, A163511, A364255 [= gcd(n,a(n))], A364287 (positions of negative terms), A364292 (of terms <= 0), A364288, A364294 [= -a(A364293(n))].
%K A364258 sign,look
%O A364258 0,3
%A A364258 _Antti Karttunen_, Jul 25 2023