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A114065 Numbers k such that the digits of phi(k) and sigma(k) are permutations of those of k. 5

%I #20 Jul 22 2021 07:53:12

%S 1,3014685,21638943,170726121,207380169,215341083,233559801,234511083,

%T 321634251,1620475083,1982243007,2019804093,2084013063,2185499607,

%U 2410658685,2653713819,2741018409,2859457041,3018792645,3075268041,3148920504,3701484126,4071408255

%N Numbers k such that the digits of phi(k) and sigma(k) are permutations of those of k.

%C Intersection of A115920 and A115921.

%H Giovanni Resta, <a href="/A114065/b114065.txt">Table of n, a(n) for n = 1..520</a> (terms < 10^12)

%e sigma(3014685) = 5431680 and phi(3014685) = 1586304.

%o (Python)

%o from sympy import totient, divisor_sigma

%o A114065_list = [n for n in range(1,10**7) if sorted(str(divisor_sigma(n))) == sorted(str(totient(n))) == sorted(str(n))] # _Chai Wah Wu_, Dec 13 2015

%o (PARI) isok(n) = (d = vecsort(digits(n))) && (ds = vecsort(digits(sigma(n)))) && (d == ds) && (de = vecsort(digits(eulerphi(n)))) && (ds == de); \\ _Michel Marcus_, Dec 13 2015

%Y Cf. A115920, A115921, A175795.

%Y Cf. A000010, A000203.

%K nonn,base

%O 1,2

%A _Giovanni Resta_, Feb 13 2006

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Last modified April 25 01:35 EDT 2024. Contains 371964 sequences. (Running on oeis4.)