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Numbers k such that k = x * A005383(i), where x is either 2, 3, 8, 9 or 15 and i > 2 [i.e., A005383(i) > 5].
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%I #6 May 25 2022 09:14:25

%S 26,39,74,104,111,117,122,146,183,195,219,296,314,333,386,471,488,549,

%T 554,555,579,584,626,657,794,831,842,914,915,939,1082,1095,1191,1226,

%U 1256,1263,1322,1346,1371,1413,1466,1514,1544,1623,1737,1754,1839,1983,1994,2019,2186,2199,2216,2271,2306,2355,2402,2426

%N Numbers k such that k = x * A005383(i), where x is either 2, 3, 8, 9 or 15 and i > 2 [i.e., A005383(i) > 5].

%C Solutions to phi(n) = phi(sigma(n)) that are given by Theorem 3 of Golomb's manuscript, i.e., a subset of all solutions (A006872).

%H S. W. Golomb, <a href="/A006872/a006872_1.pdf">Equality among number-theoretic functions</a>, Unpublished manuscript. (Annotated scanned copy)

%F For all n >= 1, A353636(a(n)) = 0.

%o (PARI)

%o A354344(n) = { if(!(n%15),n/=15,if(!(n%9),n/=9,if(!(n%8),n/=8,if(!(n%3),n/=3,if(!(n%2),n/=2,return(0)))))); ((n>5) && isprime(n) && isprime((1+n)/2)); };

%o isA354345(n) = A354344(n);

%Y Setwise difference A006872 \ A260021. Subset of positions of zeros in A353636.

%Y Cf. A005383, A354344 (characteristic function).

%K nonn

%O 1,1

%A _Antti Karttunen_, May 25 2022