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A036925
Digit sum of composite odd number equals digit sum of juxtaposition of its prime factors (counted with multiplicity).
2
27, 85, 121, 265, 319, 355, 391, 483, 517, 535, 627, 645, 663, 729, 825, 861, 895, 913, 915, 985, 1111, 1165, 1219, 1255, 1449, 1507, 1581, 1633, 1755, 1795, 1881, 1903, 1921, 1935, 2067, 2079, 2155, 2173, 2227, 2265, 2373, 2409, 2461, 2475, 2515, 2583
OFFSET
1,1
COMMENTS
Odd Smith numbers. - Robert Israel, Aug 25 2024
LINKS
MAPLE
filter:= proc(n) local F;
if isprime(n) then return false fi;
F:= ifactors(n)[2];
convert(convert(n, base, 10), `+`) = convert(map(t -> t[2]*convert(convert(t[1], base, 10), `+`), F), `+`)
end proc:
select(filter, [seq(i, i=9..10000, 2)]); # Robert Israel, Aug 25 2024
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Jan 04 1999
EXTENSIONS
Title made more precise by Sean A. Irvine, Nov 30 2020
STATUS
approved