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A248819 Numbers n such that the digits of antisigma(n) end in sigma(n). 0

%I

%S 79,479,2879,4895,26879,79999,644735,799999,2395488,6399839,8598719,

%T 63652895,144726608,799999999,935546879,12640160863,15282380799,

%U 43687707904,79999999999

%N Numbers n such that the digits of antisigma(n) end in sigma(n).

%C All the primes of the form 8*10^k-1 for k>0 are terms (A056721). - _Giovanni Resta_, May 29 2016

%e sigma(4895) = 6480 and antisigma of 4895 is (4895 * 4896) / 2 - sigma(4895) = 11982960 - 6480 = 11976480.

%p with(numtheory): P:=proc(q) local a,n;

%p for n from 1 to q do then a:=ilog10(sigma(n))+1;

%p if sigma(n)=((n*(n+1)/2-sigma(n)) mod 10^a) then print(n);

%p fi; od; end: P(10^9);

%Y Cf. A000230, A024816, A056721.

%K nonn,more,base

%O 1,1

%A _Paolo P. Lava_, Oct 15 2014

%E a(9)-a(19) from _Giovanni Resta_, May 29 2016

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Last modified September 24 03:49 EDT 2020. Contains 337316 sequences. (Running on oeis4.)