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A119398 Odd numbers taking exactly 21 steps to reach 15 in A086793. 3
628425, 824175, 1340325, 1422135, 1495725, 1729665, 1845585, 1853775, 1916145, 2001825, 2015685, 2040675, 2045505, 2091375, 2165625, 2220435, 2226609, 2264535, 2333925, 2360085, 2365965, 2379465, 2465925, 2474955, 2499255, 2511495 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Most terms are multiples of 5. In the first 130 terms, there only 19 non-multiples of 5: 2226609, 2556477, 3252249, 3496779, 3638439, 4060287, 4779621, 4821453, 5146713, 5313231, 5365899, 5504499, 5578419, 5738733, 5785857, 5845749, 6189183, 6222447, 6236769.

LINKS

Robert Israel, Table of n, a(n) for n = 1..500

MAPLE

f:= proc(n) option remember; local t;

  if kernelopts(level) > 460 then return FAIL fi;

  t:= add(convert(convert(d, base, 10), `+`), d=numtheory:-divisors(n));

  1+procname(t)

end proc:

f(15):= 0:

f(1):= FAIL:

Res:= NULL: count:= 0:

for n from 1 by 2 while count < 100 do

  if f(n) = 21 then Res:= Res, n; count:= count+1 fi;

od:

Res; # Robert Israel, Apr 03 2018

CROSSREFS

Cf. A086793, A119396-A119415.

Sequence in context: A141815 A333133 A172701 * A252894 A048924 A183678

Adjacent sequences:  A119395 A119396 A119397 * A119399 A119400 A119401

KEYWORD

base,nonn

AUTHOR

Zak Seidov, May 18 2006

EXTENSIONS

a(1)=628425 inserted by Robert Israel, Apr 03 2018

STATUS

approved

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Last modified September 20 16:50 EDT 2021. Contains 347586 sequences. (Running on oeis4.)