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 A076529 #15 Feb 24 2024 01:04:32 %S A076529 2,4,6,10,16,22,36,40,46,100,136,232,256,856,1036,1296,1540,1600,2016, %T A076529 4336,6526,9178,14400,16096,30496,55386,61132,62800,65536,72580,77616, %U A076529 110176,152650,179296,244966,299650,603460,619696,686736,1876726,2841916,3058210 %N A076529 Numbers k for which phi(k) = phi(k+1) - phi(k-1). %H A076529 Donovan Johnson, <a href="/A076529/b076529.txt">Table of n, a(n) for n = 1..100</a> %e A076529 phi(22) = 10; phi(23) = 22; phi(21) = 12 and 10 = 22 - 12; hence 22 is a term of the sequence. %t A076529 Select[Range[2, 10^5], EulerPhi[#] == EulerPhi[#+1] - EulerPhi[#-1] &] %t A076529 Flatten[ Position[Partition[EulerPhi[Range[31*10^5]],3,1],_?(#[[2]] == #[[3]] -#[[1]]&),1,Heads->False]]+1 (* _Harvey P. Dale_, Dec 28 2017 *) %Y A076529 Cf. A000010, A220160. %K A076529 nonn %O A076529 1,1 %A A076529 _Joseph L. Pe_, Oct 18 2002 %E A076529 Missing first term added by _Donovan Johnson_, Dec 06 2012