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A115527
Numbers k such that the concatenation of k with 2*k gives a square.
29
3, 8163265306122448979592, 18367346938775510204082, 32653061224489795918368, 504986744097967428355005681100871102133568993813912384800
OFFSET
1,1
EXAMPLE
3_6 = 6^2.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Jan 25 2006
STATUS
approved