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 A097008 #9 Oct 15 2013 22:32:33
%S A097008 1,2,5,11,19,43,53,101,1297,883,1009,1037,1051,985,2391,12101,13457,
%T A097008 21887,42683,69697,50177,115601,113669,88897,156817,184477,247487,
%U A097008 245029,187273,287543,211031,287093,1001447,5398093,9741229,7757137
%N A097008 a(n) = index of first appearance of n in A096862.
%C A097008 a(n) = smallest k such that A096863(k) + A096993(k) = n.
%C A097008 a(n) = smallest k such that n equals the index of the term that completes the first cycle in the trajectory of k under iteration of f(x) = A062402(x) = sigma(phi(x)).
%H A097008 Klaus Brockhaus, <a href="/A097008/b097008.txt">Table of n, a(n) for n=1..120</a>
%e A097008 The trajectory of 19 under iteration of f(x) is 19, 39, 60, 31, 72, 60, 31, 72, ...; the cycle (60, 31, 72) is completed at the fifth term and for j < 19 the first cycle in trajectory of j under iteration of f(x) is completed at the first, second, third or fourth term, hence a(5) = 19.
%e A097008 The trajectory of 247487 under iteration of f(x) is 247487, 787200, 507873, 1282842, 1395372, 1476096, 1572096, 1089403, 3669120, 2621120, 4464096, 3963960, 2946240, 2538280, 3265416, 2877420, 1965840, 2227680, 1310680, 1591200, 1277874, 1307124, 1110488, 2010960, 1488032, 1981496, 2239920, 1965840, ...; the cycle (1965840, 2227680,
%e A097008 ..., 2239920) is completed at the 27th term and for j < 247487 the first cycle in trajectory of j under iteration of f(x) is completed at an earlier term, hence a(27) = 247487.
%t A097008 sf[x_] :=DivisorSigma[1, EulerPhi[x]]; nsf[x_, ho_] :=NestList[sf, x, ho]; luf[x_, ho_] :=Length[Union[nsf[x, ho]]]; t=Table[0, {35}];Do[s=luf[n, 100]; If[s<36&&t[[s]]==0, t[[s]]=n], {n, 1, 1500000}];t
%o A097008 (PARI) {v=vector(40); for(n=1, 10000000, k=n; s=Set(k); until(setsearch(s, k=sigma(eulerphi(k))), s=setunion(s, Set(k))); a=#s; if(a<=m&&v[a]==0, v[a]=n)); v} /* Klaus Brockhaus, Jul 16 2007 */
%Y A097008 Cf. A062402, A096862, A096863, A096993, A097007.
%K A097008 nonn
%O A097008 1,2
%A A097008 _Labos Elemer_, Jul 26 2004
%E A097008 Edited, a(27) and a(33) corrected and a(34) through a(36) added by _Klaus Brockhaus_, Jul 16 2007