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A106125 Numbers k such that k divides the k-th semiprime. 2

%I #31 Oct 16 2022 03:24:31

%S 1,2,3,7,11,43,53,613367,613439,613451,613523,613549,613609,

%T 6384425461,6384425521,6384425569,6384425647

%N Numbers k such that k divides the k-th semiprime.

%C Note that except 1, all other term in the sequence will be primes.

%C a(18) > 10^12. - _Lucas A. Brown_, Oct 17 2020

%H Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/semiprimemods.py">semiprimemods.py</a>

%e a(4)=7 is a term because 7 divides the 7th semiprime (i.e., 21).

%Y Cf. A001358, A356764, A357741.

%K nonn,hard,more

%O 1,2

%A _Shyam Sunder Gupta_, May 07 2005

%E a(14)-a(17) from _Donovan Johnson_, Sep 27 2010

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Last modified March 28 05:02 EDT 2024. Contains 371235 sequences. (Running on oeis4.)