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%I #12 May 15 2017 05:06:55
%S 24,26,87,250,440,448,644,875,1320,1640,1768,1996,2480,2500,2656,4400,
%T 6544,8250,8360,8420,8727,8875,13200,16400,19984,19996,24800,25000,
%U 25424,43750,44000,45712,63528,73840,75184,82500,83346,83478,83600,84200,132000,164000
%N Number x = concat(MSD(x),b) such that MSD(x)*b = phi(x), where MSD(x) is the Most Significant Digit of x and phi(x) is the Euler totient function of x.
%C Numbers of the form 25*10^k, 44*10^k, 132*10^k, 164*10^k, 248*10^k, 825*10^k, 836*10^k, 842*10^k, 4375*10^k, 7384*10^k, etc. , with k > 0, are part of the sequence.
%H Paolo P. Lava, <a href="/A286130/b286130.txt">Table of n, a(n) for n = 1..110</a>
%e phi(63528) = 6*3528 = 21168.
%p with(numtheory): P:=proc(q) local n; for n from 1 to q do
%p if phi(n)=trunc(n/10^(ilog10(n)))*(n mod 10^ilog10(n)) then print(n); fi;
%p od; end: P(10^9);
%t Select[Range@ 164000, Function[x, First[#] FromDigits[Rest@ #] == EulerPhi@ x &@ IntegerDigits@ x]] (* _Michael De Vlieger_, May 03 2017 *)
%Y Cf. A000010, A000030.
%K nonn,base
%O 1,1
%A _Paolo P. Lava_, May 03 2017
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