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A239563 Numbers n such that there are a, b with abs(sigma(a) - sigma(b)) = sigma(n) - n and a U b = n, where U is decimal concatenation. 3
23, 47, 139, 529, 611, 911, 1109, 1445, 1621, 2003, 2521, 2531, 4007, 4361, 4879, 7169, 9011, 9013, 9481, 13009, 18883, 22081, 24257, 25031, 45349, 49901, 56081, 90011, 98941, 99101, 133705, 160031, 169181, 200003, 202289, 210181, 250031, 307289, 336961, 357101 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Paolo P. Lava and Giovanni Resta, Table of n, a(n) for n = 1..207(terms < 3*10^9, first 50 terms from Paolo P. Lava)

EXAMPLE

For n = 9481 we can consider 9481 = 9 U 481 and sigma(9481) = 10000, sigma(481) = 532, sigma(9) = 13 and 532 - 13 = 519 = 10000 - 9481.

MAPLE

with(numtheory);

T:=proc(t) local w, x, y; x:=t; y:=0; while x>0 do x:=trunc(x/10); y:=y+1; od; end:

P:=proc(q) local a, b, c, d, i, n;

for n from 1 to q do a:=sigma(n); b:=T(n);

for i from 1 to b-1 do c:=trunc(n/10^i); d:=n-c*10^i;

if abs(sigma(c)-sigma(d))=a-n then print(n); break; fi;

od; od; end: P(10^9);

CROSSREFS

Cf. A000203, A239562.

Sequence in context: A043197 A043977 A042048 * A241207 A042050 A139857

Adjacent sequences:  A239560 A239561 A239562 * A239564 A239565 A239566

KEYWORD

nonn,base

AUTHOR

Paolo P. Lava, Mar 21 2014

STATUS

approved

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Last modified April 7 04:20 EDT 2020. Contains 333292 sequences. (Running on oeis4.)