A376639 Terms of A151999 which are not a term of A293928.

10, 30, 34, 42, 50, 60, 68, 78, 90, 102, 110, 114, 126, 136, 150, 156, 170, 180, 204, 210, 220, 222, 228, 234, 250, 270, 294, 300, 306, 330, 340, 342, 378, 390, 408, 410, 420, 438, 444, 450, 456, 468, 510, 514, 540, 546, 550, 570, 578, 582, 612, 630, 654, 660, 666

Offset

1,1

Comments

Conjecture: For each a(n) there is no a(n) = A000010(a(k)), k > n.

Conjecture: Every term of A293928 exists in A151999.

Links

Table of n, a(n) for n=1..55.

Example

10 is a term because 2 divides 4 and 10 and 10 is not a term of A293928.
666 is a term because 666 is a term of A151999 and 666 is not a term of A293928 as it has no totient inverses.

Prog

(Sage)
terms = []
for n in range(1, 10000): # Equivalent of A151999/b151999.txt
    if euler_phi(n)**2 == euler_phi(euler_phi(n) * n): terms.append(n)
displayTerms = []
for n in range(0, 10000):
    searchTerms = terms[n+1::]
    found = False
    for k in range(0, len(searchTerms)):
        if terms[n] == euler_phi(searchTerms[k]):
            found = True
            break
    if False == found and n < len(terms):
        displayTerms.append(terms[n])
for n in range(0, 55):
    print(displayTerms[n], end=', ')

Crossrefs

Cf. A000010, A151999, A293928.

Sequence in context: A031195 A034117 A104863 * A362047 A326122 A027183

Adjacent sequences: A376636 A376637 A376638 * A376640 A376641 A376642

Keyword

nonn

Author

Torlach Rush, Sep 30 2024

Status

approved