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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

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

LINKS

Table of n, a(n) for n=1..18.

Eric Weisstein's World of Mathematics, See also.

L. Marmet, Results

L. Marmet, About a(16), a(17) and a(18).

L. Marmet, First occurrences of squarefree gaps...

EXAMPLE

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

PROG

(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); }

a(n) = {my(x = 1); while (! iscons(x, n), x++); x; } \\ Michel Marcus, Jan 13 2014

CROSSREFS

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

Sequence in context: A054881 A076687 A045882 * A267987 A056407 A056397

Adjacent sequences:  A051678 A051679 A051680 * A051682 A051683 A051684

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

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Last modified May 28 00:36 EDT 2017. Contains 287210 sequences.