A302921 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.

20, 204, 444, 564, 744, 1160, 1284, 1416, 1644, 1704, 1812, 2124, 2172, 2480, 2604, 2844, 2892, 2964, 3084, 3156, 3192, 3320, 3324, 3396, 3492, 3560, 3576, 3756, 3972, 4164, 4404, 4476, 4520, 4572, 4740, 4764, 5004, 5352, 5360, 5364, 5496, 5532, 5604, 5772, 5840, 6320

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems (invphi.gp).

Formula

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

Example

20 is a term because 25 is the least solution of 20 = A000010(x) and gcd(20,25) equals the number of solutions 5.
7812 is a term because 9121 is the least solution of 7812 = A000010(x) and gcd(7813,9121) equals the number of solutions 7.
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.

Prog

(PARI) is(k) = gcd(k, invphiMin(k)) == invphiNum(k); \\ Amiram Eldar, Nov 16 2024, using Max Alekseyev's invphi.gp

Crossrefs

Subsequence of A302838.

Cf. A000010, A002202.

Sequence in context: A041766 A121088 A302838 * A334692 A325474 A364651

Adjacent sequences: A302918 A302919 A302920 * A302922 A302923 A302924

Keyword

nonn

Author

Torlach Rush, Apr 15 2018

Extensions

More terms from Amiram Eldar, Nov 16 2024

Status

approved