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A051681 Smallest term of first run of exactly n consecutive integers which are not squarefree. 14

%I

%S 4,8,48,242,844,22020,217070,1092747,8870024,262315467,221167422,

%T 47255689915,82462576220,1043460553364,79180770078548,

%U 3215226335143218,23742453640900972,125781000834058568

%N Smallest term of first run of exactly n consecutive integers which are not squarefree.

%D a(16) was obtained as a result of a team effort by Z. McGregor-Dorsey et al.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Squarefree.html">See also.</a>

%H L. Marmet, <a href="http://www.marmet.org/louis/sqfgap/results.html">Results</a>

%H L. Marmet, <a href="http://www.marmet.org/louis/sqfgap/index.html#acknowledgements">About a(16), a(17) and a(18).</a>

%H L. Marmet, <a href="http://www.marmet.org/louis/sqfgap/">First occurrences of squarefree gaps...</a>

%e n=5 -> {844=2^2.211; 845=5.13^2; 846=2.3^2.47; 847=7.11^2; 848=2^4.53}

%o (PARI) iscons(x, n) = {if (issquarefree(x-1) && issquarefree(x+n), for (k = 0, n-1, if (issquarefree(x+k), return (0));); return (1);); return (0);}

%o a(n) = {my(x = 1); while (! iscons(x, n), x++); x;} \\ _Michel Marcus_, Jan 13 2014

%Y Cf. A045882 (another version), A013929, A053806.

%K nice,nonn

%O 1,1

%A Louis Marmet (louis(AT)marmet.org) and David Bernier (ezcos(AT)yahoo.com)

%E a(16) reported by Louis Marmet (louis(AT)marmet.org), Jul 24 2000

%E a(17) was obtained as a result of a team effort by E. Wong et al.

%E a(18) = 125781000834058568 was obtained as a result of a team effort by L. Marmet et al.

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Last modified March 25 11:34 EDT 2017. Contains 284076 sequences.