

A051681


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


14



4, 8, 48, 242, 844, 22020, 217070, 1092747, 8870024, 262315467, 221167422, 47255689915, 82462576220, 1043460553364, 79180770078548, 3215226335143218, 23742453640900972, 125781000834058568
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OFFSET

1,1


REFERENCES

a(16) was obtained as a result of a team effort by Z. McGregorDorsey et al.


LINKS



EXAMPLE

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


MATHEMATICA

Module[{tb=Table[If[SquareFreeQ[n], 0, 1], {n, 11*10^5}]}, Table[ SequencePosition[ tb, PadRight[{}, k, 1], 1][[All, 1]], {k, 8}]]//Flatten (* The program generates the first 8 terms of the sequence. To generate more, increase the constants for n and k but the program may take a long time to run. *) (* Harvey P. Dale, Mar 24 2022 *)


PROG

(PARI) iscons(x, n)=if (issquarefree(x1) && issquarefree(x+n), for (k = 0, n1, if (issquarefree(x+k), return (0)); ); return (1); ); return (0);
a(n) = {my(x = 1); while (! iscons(x, n), x++); x; } \\ Michel Marcus, Jan 13 2014


CROSSREFS



KEYWORD

nice,nonn


AUTHOR

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


EXTENSIONS

a(16) reported by Louis Marmet (louis(AT)marmet.org), Jul 24 2000
a(17) was obtained as a result of a team effort by E. Wong et al.
a(18) = 125781000834058568 was obtained as a result of a team effort by L. Marmet et al.


STATUS

approved



