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A154534
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Odd nonprimes n with smallest digit of n + number of smallest digits of n = odd nonprime.
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1
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77, 105, 201, 203, 205, 207, 209, 301, 303, 305, 309, 403, 405, 407, 501, 505, 507, 603, 605, 609, 703, 705, 707, 779, 801, 803, 805, 807, 899, 901, 903, 905, 909, 989, 1011, 1015, 1017, 1023, 1025, 1027, 1029, 1035, 1037, 1041, 1043, 1045, 1047, 1053, 1055
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OFFSET
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1,1
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LINKS
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EXAMPLE
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If n=77=odd nonprime, 7=7 and 7+2=9=odd nonprime, thus 77 is in the sequence. If n=105=odd nonprime, 0<1<5 and 0+1=1=odd nonprime, thus 105 is in the sequence.
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MAPLE
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filter:= proc(n) local L, m, q;
if isprime(n) then return false fi;
L:= convert(n, base, 10);
m:= min(L);
q:= m + numboccur(L, m);
q::odd and not isprime(q)
end proc:
select(filter, [seq(2*i+1, i=0..1000)]); # Robert Israel, Apr 15 2015
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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