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%I #14 Apr 14 2019 10:59:13
%S 127251,649375,1274373,1303047,2206519,2388123,2775625,3400623,
%T 3585625,3627909,4193125,4294375,4311873,5707177,6319375,6336873,
%U 6926875,7128567,7939375,7949581,8101537,11280625,11298123,11786875
%N Odd n such that tau(n) = tau(n+2) = 10, where tau(n) = A000005(n) is the number of divisors of n.
%H Harry J. Smith, <a href="/A066690/b066690.txt">Table of n, a(n) for n = 1..1000</a>
%t Do[ If[ DivisorSigma[0, 2n - 1] == DivisorSigma[0, 2n + 1] == 10, Print[2n - 1]], {n, 1, 10^7} ]
%t 2*SequencePosition[Table[If[DivisorSigma[0,n]==10,1,0],{n,1,11786879,2}],{1,1}][[All,1]]-1 (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Apr 14 2019 *)
%o (PARI) for (n=1,2000000, if ((numdiv(2*n-1)==10) && (numdiv(2*n+1)==10), write("tau=tau=10.txt",2*n-1,"::",tau(2*n-1))))
%o (PARI) { n=0; for (m=1, 10^10, if ((numdiv(2*m-1)==10) && (numdiv(2*m+1)==10), write("b066690.txt", n++, " ", 2*m-1); if (n==1000, return)) ) } \\ _Harry J. Smith_, Mar 17 2010
%K nonn
%O 1,1
%A _Jon Perry_, Jan 11 2002
%E Edited by _Dean Hickerson_, Jan 13 2002
%E OFFSET changed from 0 to 1 by _Harry J. Smith_, Mar 17 2010
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