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%I #10 Apr 30 2020 03:25:45
%S 1,2,3,15,255,735,2624,3135,4095,4784,5264,5984,7215,7424,7904,9344,
%T 10064,10335,10815,11024,11984,12375,12495,13695,16184,16575,22575,
%U 22784,22815,26144,26264,27104,30015,30855,30975,32384,33824,34335,34544,38024,38415,39104
%N Numbers k such that k and k+1 are both phi-practical numbers (A260653).
%H Amiram Eldar, <a href="/A330871/b330871.txt">Table of n, a(n) for n = 1..10000</a>
%e 1 is a term since both 1 and 2 are phi-practical numbers.
%t phiPracticalQ[n_] := If[n<1, False, If[n==1, True, (lst = Sort @ EulerPhi @ Divisors[n]; ok=True; Do[If[lst[[m]]>Sum[lst[[l]], {l, 1, m-1}]+1, (ok=False; Break[])], {m, 1, Length[lst]}]; ok)]]; Select[Range[40000], phiPracticalQ[#] && phiPracticalQ[#+1] &] (* after Frank M Jackson at A260653 *)
%Y Cf. A260653, A287681.
%K nonn
%O 1,2
%A _Amiram Eldar_, Apr 29 2020