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A130891
a(n) = n if n is not an odd prime number. Otherwise, a(n) = k*floor(n/10), where k is the smallest integer such that n < 10^k.
0
0, 1, 2, 0, 4, 0, 6, 0, 8, 9, 10, 2, 12, 2, 14, 15, 16, 2, 18, 2, 20, 21, 22, 4, 24, 25, 26, 27, 28, 4, 30, 6, 32, 33, 34, 35, 36, 6, 38, 39, 40, 8, 42, 8, 44, 45, 46, 8, 48, 49, 50, 51, 52, 10, 54, 55, 56, 57, 58, 10, 60, 12, 62, 63, 64, 65, 66, 12, 68
OFFSET
0,3
MAPLE
f:= proc(n) local k;
if n::odd and isprime(n) then
k:= ilog10(n)+1;
k*floor(n/10)
else n
fi
end proc:
map(f, [$0..100]); # Robert Israel, Aug 04 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Mohammad K. Azarian, Aug 21 2007
EXTENSIONS
Offset changed by Mohammad K. Azarian, Nov 19 2008
Offset corrected by Robert Israel, Aug 04 2019
STATUS
approved