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 A269861 #14 Mar 20 2016 12:55:10 %S A269861 4,5,7,10,12,14,15,16,17,19,21,29,30,34,36,38,40,41,42,43,44,45,48,51, %T A269861 52,53,55,56,57,58,61,63,64,65,67,73,77,79,82,86,87,90,91,92,100,101, %U A269861 102,103,106,108,110,113,114,115,120,122,123,124,125,126,127,129,130,132,134,135,136,137,140,144,146,148,149 %N A269861 Numbers n such that n and A048673(n) are of opposite parity. %C A269861 Union of even terms of A246261 and odd terms of A246263. %H A269861 Antti Karttunen, <a href="/A269861/b269861.txt">Table of n, a(n) for n = 1..10000</a> %F A269861 Other identities. For all n >= 1: %F A269861 A269862(a(n)) = n. %t A269861 f[n_] := (Times @@ Power[If[# == 1, 1, NextPrime@ #] & /@ First@ #, Last@ #] + 1)/2 &@ Transpose@ FactorInteger@ n; Select[Range@ 150, Xor[EvenQ@ f@ #, EvenQ@ #] &] (* _Michael De Vlieger_, Mar 17 2016 *) %o A269861 (Scheme, with _Antti Karttunen_'s IntSeq-library) %o A269861 (define A269861 (NONZERO-POS 1 1 (lambda (n) (- (A000035 n) (A000035 (A048673 n)))))) %Y A269861 Complement: A269860. %Y A269861 Left inverse: A269862. %Y A269861 Cf. A000035, A048673, A246261, A246263. %Y A269861 Cf. also A270431. %K A269861 nonn %O A269861 1,1 %A A269861 _Antti Karttunen_, Mar 16 2016