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A353746
Numbers k for which phi(sigma(k)) + A064989(sigma(k)) is equal to phi(k) + A064989(k).
0
1, 114, 618, 2428, 3868, 11706, 16012, 23946, 2031108, 2938902, 3531102, 10475862, 98250486, 205600756
OFFSET
1,2
COMMENTS
Numbers k such that A353747(k) = A353747(sigma(k)), or equally that A062401(k) + A350073(k) = A000010(k) + A064989(k).
When A003961(x) is substituted for k, the condition becomes: numbers x such that phi(A003973(x))+A326042(x) = A003972(x)+x, i.e. A353747(A003973(x)) - x = A003972(x).
a(15) > 1442840576, if it exists.
PROG
(PARI)
A064989(n) = { my(f=factor(n>>valuation(n, 2))); for(i=1, #f~, f[i, 1] = precprime(f[i, 1]-1)); factorback(f); };
isA353746(n) = { my(s=sigma(n)); ((eulerphi(s)+A064989(s))==(eulerphi(n)+A064989(n))); };
KEYWORD
nonn,more
AUTHOR
Antti Karttunen, May 06 2022
STATUS
approved