A230289 Let m = n-th number not divisible by 3 (A001651); a(n) = position of m in A065075, or -1 if never appears in A065075.

1, 3, 4, 7, 6, 5, 8, 9, 10, 13, 24, 41, 26, 51, 64, 151, 276, 335, 446, 219, 550, 451, 1674, 1685, 2192, 2667, 9220, 17647, 3972, 9221, 17648, 25311, 35776, 25339, 147018, 112397, 146972, 212667, 243892, 243871, 963024, 1263521, 1838078, 2380569, 2380378

Offset

1,2

Comments

It is believed that a(n) is always > 0.

Links

Lars Blomberg, Table of n, a(n) for n = 1..86

Index entries for Colombian or self numbers and related sequences

Maple

read transforms; M:=100000; sp:=1; a:=[sp]; s:=sp;
for n from 2 to M do sp:=digsum(s); a:=[op(a), sp]; s:=s+sp; od:
b:=[]:
for n from 1 to 100 do
if (n mod 3) <> 0 then
if member(n, a, 'p') then b:=[op(b), p] else b:=[op(b), -1]; fi;
fi;
od:
b;

Crossrefs

Cf. A065075, A001651.

Sequence in context: A348987 A322656 A105827 * A367502 A023888 A222085

Adjacent sequences: A230286 A230287 A230288 * A230290 A230291 A230292

Keyword

nonn,base

Author

N. J. A. Sloane, Oct 17 2013

Extensions

a(35)-a(45) from Lars Blomberg, Jul 31 2017

Status

approved