

A058218


Positive integers that cannot be represented in the form n=5ab+a+b for any choice of nonzero integers a and b (positive or negative).


1



1, 2, 4, 6, 8, 10, 12, 14, 18, 22, 26, 28, 30, 32, 36, 40, 44, 48, 50, 54, 58, 60, 62, 66, 76, 78, 82, 84, 94, 96, 98, 100, 102, 104, 114, 116, 120, 126, 132, 136, 138, 140, 144, 150, 154, 158, 162, 166, 170, 176, 184, 188, 190, 198, 202, 204, 208, 210, 212, 216, 220
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OFFSET

1,2


COMMENTS

All terms except 1 are even.  Robert Israel, Apr 07 2019


LINKS

Robert Israel, Table of n, a(n) for n = 1..10000
Maria Suzuki, Related to Alternative Formulations of the Twin Prime Problem, American Math. Monthly, 107 (2000) pp. 5556.


MAPLE

filter:= proc(n)
nops(select(t > t mod 5 = 1 or t mod 5 = 4, numtheory:divisors(5*n+1))) = 2
and nops(select(t > t mod 5 = 4, numtheory:divisors(5*n1)))=1
end proc:
select(filter, [$1..1000]); # Robert Israel, Apr 07 2019


CROSSREFS

A002822 results if the coefficient 5 in the definition above is replaced by 6.
Includes 2*A124518.
Sequence in context: A098807 A189562 A194372 * A264986 A140955 A111905
Adjacent sequences: A058215 A058216 A058217 * A058219 A058220 A058221


KEYWORD

nonn


AUTHOR

John W. Layman, Nov 30 2000


STATUS

approved



