A116098 Numbers k such that k concatenated with k-9 gives the product of two numbers which differ by 6.
11, 101, 1001, 10001, 100001, 1000001, 10000001, 100000001, 1000000001, 10000000001, 13223140496, 20661157025, 29752066116, 40495867769, 52892561984, 66942148761, 82644628100, 100000000001, 1000000000001
Offset: 1
Examples
100000001//99999992 = 99999998 * 100000004, where // denotes concatenation.
Links
- Robert Israel, Table of n, a(n) for n = 1..134
Crossrefs
Programs
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Maple
g:= proc(d) local r,c,a,b; r:= mul(t[1],t=select(s -> s[2]::odd, ifactors(10^d+1)[2])) c:= ceil((10^(d-1)+9)/r); a:= isqrt(c); if a^2 < c then a:= a+1 fi; c:= floor((10^d+8)/r); b:= isqrt(c); if b^2 > c then b:= b-1 fi; seq(r*y^2, y = a..b) end proc: seq(g(d),d=1..60); # Robert Israel, Aug 13 2018
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