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A116185
Numbers k such that k concatenated with k+4 gives the product of two numbers which differ by 3.
6
150, 186, 324, 376, 666, 2046, 3000, 82650, 100384, 466716, 1322316, 4049584, 67820074, 110003884, 135734074, 156502836, 196043286, 213017754, 238849000, 261405396, 289940826, 310507774, 365294050, 398891964, 446667216
OFFSET
1,1
COMMENTS
Also numbers k such that k concatenated with k+6 gives the product of two numbers which differ by 1.
MAPLE
cc:=proc(x, y) local s: s:=proc(m) nops(convert(m, base, 10)) end: x*10^s(y)+y: end: a:=proc(n) if type(sqrt(9+4*cc(n, n+4)), integer) then n else fi end: seq(a(n), n=1..500000); # very slow; cc yields the concatenation of x and y; - Emeric Deutsch, May 05 2007
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Feb 06 2006
EXTENSIONS
Edited by N. J. A. Sloane, Apr 14 2007
STATUS
approved