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A069526
Smallest multiple of n with digit sum = 7, or 0 if no such number exists, e.g. a(3k)= a(11k) = 0.
6
7, 16, 0, 16, 25, 0, 7, 16, 0, 70, 0, 0, 52, 70, 0, 16, 34, 0, 133, 160, 0, 0, 115, 0, 25, 52, 0, 700, 232, 0, 124, 160, 0, 34, 70, 0, 0, 304, 0, 160, 205, 0, 43, 0, 0, 322, 1222, 0, 2401, 250, 0, 52, 106, 0, 0, 7000, 0, 232, 4012, 0, 61, 124, 0, 1024, 520, 0, 11122, 340
OFFSET
1,1
COMMENTS
Either no multiples of 37 have digit sum 7 or their first values are > 10000000. - Larry Reeves (larryr(AT)acm.org), Jul 02 2002
No multiples of 3, 11, 37, 101 or 271 have digit sum 7. - Robert Israel, Feb 13 2024
LINKS
FORMULA
a(n)= n*A088396(n). - R. J. Mathar, Aug 06 2019
MAPLE
unfinished:= true: V:= Vector(300): V0:= select(t -> igcd(t, 3*11*37*101*271) = 1, {$1..300}):
for i1 from 0 while unfinished do
for i2 from 0 to i1 while unfinished do
for i3 from 0 to i2 while unfinished do
for i4 from 0 to i3 while unfinished do
for i5 from 0 to i4 while unfinished do
for i6 from 0 to i5 while unfinished do
for i7 from 0 to i6 while unfinished do
v:= 10^i1 + 10^i2 + 10^i3 + 10^i4 + 10^i5 + 10^i6 + 10^i7;
dv:= numtheory:-divisors(v);
for s in V0 intersect dv do
V[s]:= v;
od;
V0:= V0 minus dv;
unfinished:= evalb(V0 <> {});
od od od od od od od:
convert(V, list); # Robert Israel, Feb 13 2024
KEYWORD
nonn,look,base
AUTHOR
Amarnath Murthy, Apr 01 2002
EXTENSIONS
More terms from Larry Reeves, Jul 02 2002
STATUS
approved