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%I #12 May 28 2018 08:02:04
%S 1,10,9,26,25,74,169,82,441,170,133,348,6889,166,3025,344,559,1602,
%T 9981,820,9979,986,4333,1236,9191,694,3249,1652,3481,9378,34969,3118,
%U 859329,5636,36829,3324,51947,3994,6561,5000,15835,16806,944741,6436,119025
%N a(n) is the smallest nonprime k such that tau(k + n) = tau(k) + n , where tau(n) is the number of divisors of n (A000005).
%e n=5: a(5)=25 because tau(25)+5 = 3+5 = 8 = tau(25+5) = tau(30).
%t ds[x_, de_] :=DivisorSigma[0, x+de]-DivisorSigma[0, x]-de; a[n_] :=Block[{m=1, s=ds[m, n]}, While[(s!=0||PrimeQ[m])&&!Greater[m, 10000000], m++ ];m];
%Y Cf. A000005, A054905, A305196.
%K nonn
%O 1,2
%A _Labos Elemer_, Nov 02 2004
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