A302921 - OEIS

%I #19 Nov 16 2024 02:53:41

%S 20,204,444,564,744,1160,1284,1416,1644,1704,1812,2124,2172,2480,2604,

%T 2844,2892,2964,3084,3156,3192,3320,3324,3396,3492,3560,3576,3756,

%U 3972,4164,4404,4476,4520,4572,4740,4764,5004,5352,5360,5364,5496,5532,5604,5772,5840,6320

%N Values of A000010(m) where gcd(A000010(m), m) equals the number of solutions of A000010(m) = A000010(x), and m is the least solution.

%H Amiram Eldar, <a href="/A302921/b302921.txt">Table of n, a(n) for n = 1..10000</a>

%H Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp).

%F gcd(A000010(m), m) = #{A000010(m) = A000010(x)}.

%e 20 is a term because 25 is the least solution of 20 = A000010(x) and gcd(20,25) equals the number of solutions 5.

%e 7812 is a term because 9121 is the least solution of 7812 = A000010(x) and gcd(7813,9121) equals the number of solutions 7.

%e 1764 is not a term because 2107 is the least solution of 1764 = A000010(x) and gcd(1764,2107) = 49 does not equal the number of solutions 7.

%o (PARI) is(k) = gcd(k, invphiMin(k)) == invphiNum(k); \\ _Amiram Eldar_, Nov 16 2024, using _Max Alekseyev_'s invphi.gp

%Y Subsequence of A302838.

%Y Cf. A000010, A002202.

%K nonn

%O 1,1

%A _Torlach Rush_, Apr 15 2018

%E More terms from _Amiram Eldar_, Nov 16 2024