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A070837 Smallest number k such that abs(k - R(k)) = 9n, where R(k) is digit reversal of k (A004086); or 0 if no such k exists. 3
10, 13, 14, 15, 16, 17, 18, 19, 90, 1011, 100, 0, 0, 0, 0, 0, 0, 0, 0, 1021, 1090, 103, 0, 0, 0, 0, 0, 0, 0, 1031, 1080, 0, 104, 0, 0, 0, 0, 0, 0, 1041, 1070, 0, 0, 105, 0, 0, 0, 0, 0, 1051, 1060, 0, 0, 0, 106, 0, 0, 0, 0, 1061, 1050, 0, 0, 0, 0, 107, 0, 0, 0, 1071, 1040, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If 9n < 1000, k has at most 5 digits, and abs(k - R(k)) = 9n, then 10 must divide n. - Sascha Kurz, Jan 02 2003

LINKS

Table of n, a(n) for n=1..76.

MATHEMATICA

a = Table[0, {50}]; Do[d = Abs[n - FromDigits[ Reverse[ IntegerDigits[n]]]] / 9; If[d < 51 && a[[d]] == 0, a[[d]] = n], {n, 1, 10^7}]; a

PROG

(Python)

def back_difference(n):

...r = int(str(n)[::-1])

...return abs(r-n)

.

def a070837(n):

...i = 0

...while True:

......if back_difference(i)==9*n:

.........return i

......i+=1

# Christian Perfect, Jul 23 2015

CROSSREFS

Cf. A004086, A056965, A070838.

Sequence in context: A241144 A102362 A327270 * A188643 A087140 A226778

Adjacent sequences:  A070834 A070835 A070836 * A070838 A070839 A070840

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, May 12 2002

EXTENSIONS

More terms from Sascha Kurz, Jan 02 2003

a(21) corrected by Christian Perfect, Jul 23 2015

STATUS

approved

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Last modified February 17 02:22 EST 2020. Contains 331976 sequences. (Running on oeis4.)