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A132359 Numbers divisible by the square of their last decimal digit. 7
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

This is a 10-automatic sequence. - Charles R Greathouse IV, Dec 28 2011

LINKS

T. D. Noe and Christian N. K. Anderson, Table of n, a(n) for n = 1..10000 (first 1000 values from T. D. Noe)

Index entries for 10-automatic sequences.

FORMULA

Numbers n such that fp[n / (n mod 10)] = 0.

a(n) ~ 6350400n/1241929 = 5.113...n. [Charles R Greathouse IV, Dec 28 2011]

EXAMPLE

147 belongs to the sequence because 147/7^2=3.

MAPLE

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

MATHEMATICA

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 *)

PROG

(PARI) is(n)=n%(n%10)^2==0 \\ Charles R Greathouse IV, Dec 28 2011

(R) which(sapply(1:500, function(x) isint(x/(x%%10)^2))) # Christian N. K. Anderson, May 04 2013

CROSSREFS

Cf. A034709, A225722, A221651, A225296, A225297, A034709, A034837, A005349, A007602, A034838, A225297.

Sequence in context: A303446 A107478 A153146 * A131363 A089185 A098754

Adjacent sequences:  A132356 A132357 A132358 * A132360 A132361 A132362

KEYWORD

base,easy,nonn,nice

AUTHOR

Jonathan Vos Post, Nov 08 2007

EXTENSIONS

Corrected and extended by Stefan Steinerberger, Emeric Deutsch and R. J. Mathar, Nov 12 2007

STATUS

approved

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Last modified October 23 17:37 EDT 2021. Contains 348215 sequences. (Running on oeis4.)