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 A280936 Numbers k such that phi(k) = rad(k) * sopfr(k), where phi(k) is the Euler totient function of k, rad(k) the squarefree kernel of k and sopfr(k) the integer log of k. 0
 288, 1225, 4116, 35378, 54450, 1693776, 5969418, 9396618 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE Prime factors of 288 are 2, 2, 2, 2, 2, 3, 3. Then phi(288) = 96, rad(288) = 2 * 3 = 6, sopfr(288) = 2 + 2 + 2 + 2 + 2 + 3 + 3 = 16 and 6 * 16 = 96. MAPLE with(numtheory): P:=proc(q) local a, k, n; for n from 1 to q do a:=ifactors(n)[2]; if phi(n)=mul(a[k][1], k=1..nops(a))*add(a[k][1]*a[k][2], k=1..nops(a)) then print(n); fi; od; end: P(10^9); CROSSREFS Cf. A000010, A001414, A007947. Sequence in context: A281236 A237369 A339469 * A250871 A128392 A296784 Adjacent sequences:  A280933 A280934 A280935 * A280937 A280938 A280939 KEYWORD nonn,more AUTHOR Paolo P. Lava, Jan 11 2017 STATUS approved

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Last modified August 2 02:53 EDT 2021. Contains 346409 sequences. (Running on oeis4.)