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A132359
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Numbers divisible by the square of their last decimal digit.
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7
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1, 11, 12, 21, 25, 31, 32, 36, 41, 51, 52, 61, 63, 64, 71, 72, 75, 81, 91, 92, 101, 111, 112, 121, 125, 128, 131, 132, 141, 144, 147, 151, 152, 153, 161, 171, 172, 175, 181, 191, 192, 201, 211, 212, 216, 221, 224, 225, 231, 232, 241, 243, 251, 252, 261, 271, 272
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OFFSET
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1,2
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COMMENTS
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Subsequences are A017281 and A053742 representing last digits 1 and 5. Generators for the subsequences representing last digits 2, 3, 4, 6, 7, 8 and 9 are, in that order, the terms 12+20i, 63+90i, 64+80i, 36+180i, 147+490i, 128+320i, 729+810i, where i=0,1,2,... - R. J. Mathar, Nov 13 2007
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LINKS
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FORMULA
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Numbers k such that fp[k / (k mod 10)] = 0.
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EXAMPLE
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147 belongs to the sequence because 147/7^2 = 3.
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MAPLE
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isA132359 := proc(n) local ldig ; ldig := n mod 10 ; if ldig <> 0 and n mod (ldig^2) = 0 then true ; else false ; fi ; end: for n from 1 to 400 do if isA132359(n) then printf("%d, ", n) ; fi ; od: # R. J. Mathar, Nov 13 2007
a:=proc(n) local nn: nn:=convert(n, base, 10): if 0 < nn[1] and `mod`(n, nn[1]^2) =0 then n else end if end proc: seq(a(n), n=1..250); # Emeric Deutsch, Nov 15 2007
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MATHEMATICA
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Select[Range[250], IntegerDigits[ # ][[ -1]] > 0 && Mod[ #, IntegerDigits[ # ][[ -1]]^2] == 0 &] (* Stefan Steinerberger, Nov 12 2007 *)
dsldQ[n_]:=Module[{lidnsq=Last[IntegerDigits[n]]^2}, lidnsq!=0 && Divisible[n, lidnsq]]; Select[Range[300], dsldQ] (* Harvey P. Dale, May 03 2011 *)
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PROG
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(Python)
def ok(n): return n%10 > 0 and n%(n%10)**2 == 0
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CROSSREFS
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Cf. A034709, A225722, A221651, A225296, A225297, A034709, A034837, A005349, A007602, A034838, A225297.
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KEYWORD
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base,easy,nonn,nice
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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