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A246854 Numbers n such that sigma(n+4) - sigma(n) = n + 4. 4

%I

%S 1,4,26,122,146,458,746,3746,47612,16065500,388978292,5313509288,

%T 64278616556

%N Numbers n such that sigma(n+4) - sigma(n) = n + 4.

%C Also numbers n such that A001065(n+4) = A000203(n). - _Michel Marcus_, Sep 06 2014

%C a(14) (if it exists) > 10^11. - _Hiroaki Yamanouchi_, Sep 10 2014

%C a(14) (if it exists) > 10^13. - _Giovanni Resta_, Jul 13 2015

%e Number 26 is in sequence because sigma(26+4) - sigma(26) = 72 - 42 = 30 = 26 + 4.

%o (MAGMA) [n:n in[1..10^7] | SumOfDivisors(n+4)-SumOfDivisors(n) eq n+4]

%o (PARI)

%o for(n=1,10^7,if(sigma(n+4)-sigma(n)==n+4,print1(n,", "))) \\ _Derek Orr_, Sep 05 2014

%Y Cf. A000203, A067816, A246851, A246852, A246853, A246855.

%K nonn,more

%O 1,2

%A _Jaroslav Krizek_, Sep 05 2014

%E a(10)-a(13) from _Hiroaki Yamanouchi_, Sep 10 2014

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Last modified November 14 09:51 EST 2019. Contains 329111 sequences. (Running on oeis4.)