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 A270430 #11 Mar 20 2016 12:56:09 %S A270430 1,2,3,4,5,8,9,10,12,13,16,17,20,25,26,27,29,30,31,32,33,34,36,37,39, %T A270430 40,41,42,48,49,50,52,53,58,62,64,65,68,69,74,75,77,80,81,82,85,90,93, %U A270430 97,98,99,100,101,102,104,105,106,108,109,111,113,114,116,117,120,121,124,125,126,128,130,132,133,136,137,139,141,144 %N A270430 Numbers n such that A048673(n) and A064216(n) are of the same parity. %C A270430 See A270434 for the possible bias favoring this sequence over the complement A270431. %H A270430 Antti Karttunen, <a href="/A270430/b270430.txt">Table of n, a(n) for n = 1..17000</a> %F A270430 Other identities. For all n >= 1: %F A270430 A270432(a(n)) = n. %t A270430 f[n_] := (Times @@ Power[If[# == 1, 1, NextPrime@ #] & /@ First@ #, Last@ #] + 1)/2 &@ Transpose@ FactorInteger@ n; g[n_] := Times @@ Power[If[# == 1, 1, NextPrime[#, -1]] & /@ First@ #, Last@ #] &@ Transpose@ FactorInteger[2 n - 1]; Select[Range@ 144, Xor[EvenQ@ f@ #, OddQ@ g@ #] &] (* _Michael De Vlieger_, Mar 17 2016 *) %o A270430 (Scheme, with _Antti Karttunen_'s IntSeq-library) %o A270430 (define A270430 (ZERO-POS 1 1 (lambda (n) (- (A000035 (A048673 n)) (A000035 (A064216 n)))))) %Y A270430 Complement: A270431. %Y A270430 Left inverse: A270432. %Y A270430 Cf. A245449 (a subsequence). %Y A270430 Cf. A000035, A048673, A064216, A270434. %Y A270430 Cf. also A269860. %K A270430 nonn %O A270430 1,2 %A A270430 _Antti Karttunen_, Mar 17 2016