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A180479 Numbers n such that n/k is an integer. n=(x_1 x_2 ... x_r) where x_i are digits of n, k = x_1*r + x_2*(r-1) + ... + x_r*1. 1
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, 20, 24, 30, 32, 36, 40, 48, 50, 60, 64, 70, 80, 90, 96, 110, 112, 132, 170, 184, 220, 224, 225, 252, 264, 275, 312, 330, 336, 340, 342, 396, 414, 418, 440, 441, 448, 510, 550, 621, 624, 660, 665, 680, 684, 770, 812, 825, 828 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

From Michel Marcus, Aug 18 2015: (Start)

Integers n such that n and n+1 are in the sequence: 1, 2, 3, 4, 5, 6, 7, 8, 9, 224, 440, 2046, 3604, 4255, 6255, 10511, 11190,, ...

Integers n such that n, n+1 and n+2 are in the sequence: 1, 2, 3, 4, 5, 6, 7, 8, 140607, 411904, 1099448, 1101150, 2109074, 2110158, ...

(End)

LINKS

Paolo P. Lava, Table of n, a(n) for n = 1..10000

EXAMPLE

n=132, r=3, 132/(1*3+3*2+2*1)=12, n=132 belongs to the sequence.

MAPLE

with(numtheory): P:=proc(q) local a, b, k, n; for n from 1 to q do a:=n; b:=0;

for k from 1 to ilog10(n)+1 do  b:=b+(a mod 10)*k; a:=trunc(a/10); od;

if b>0 then if type(n/b, integer) then print(n); fi; fi; od; end: P(10^9);  # Paolo P. Lava, Aug 18 2015

MATHEMATICA

Select[Range[1000], Mod[#, Total[ IntegerDigits[#] Reverse@ Range@ IntegerLength@ #]] == 0 &] (* Giovanni Resta, Aug 18 2015 *)

PROG

(PARI) isok(n) = {my(d = digits(n)); ! (n % sum(kk=1, #d, d[kk]*(#d-kk+1))); } \\ Michel Marcus, Aug 18 2015

CROSSREFS

Cf. A005349, A007602, A180468.

Sequence in context: A017903 A005711 A059765 * A193456 A143289 A064807

Adjacent sequences:  A180476 A180477 A180478 * A180480 A180481 A180482

KEYWORD

base,easy,nonn,changed

AUTHOR

Ctibor O. Zizka, Sep 07 2010

STATUS

approved

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Last modified August 29 23:27 EDT 2015. Contains 261200 sequences.