cp's OEIS Frontend

A257892 Numbers n with property that A062234(n) = A062234(n+1) = A062234(n+2) = A062234(n+3).

%I A257892 #17 May 31 2015 07:57:39
%S A257892 332,878,1999,3949,4524,5953,6576,8676,10068,11840,17107,17208,19034,
%T A257892 19525,46771,46828,52767,54567,54927,56879,58695,61748,65926,77168,
%U A257892 77676,79722,92775,92823,96099,101607,111007,136141,160095,160418,173404
%N A257892 Numbers n with property that A062234(n) = A062234(n+1) = A062234(n+2) = A062234(n+3).
%C A257892 a(n) = A258432(m), where m such that A258383(m) = 4. - _Reinhard Zumkeller_, May 31 2015
%H A257892 Reinhard Zumkeller, <a href="/A257892/b257892.txt">Table of n, a(n) for n = 1..110</a>
%e A257892 a(1) = A258437(A258432(4)) = 332. - _Reinhard Zumkeller_, May 31 2015
%o A257892 (PARI) d(k) = 2*prime(k)-prime(k+1);
%o A257892 isok(n) = (d(n) == d(n+1)) && (d(n+1) == d(n+2)) && (d(n+2) == d(n+3)); \\ _Michel Marcus_, May 29 2015
%o A257892 (Perl) use Math::Prime::Util::PrimeArray; tie my @prime,"Math::Prime::Util::PrimeArray"; sub d { 2*$prime[$_[0]-1] - $prime[$_[0]] } for (1..1e6) { my $dk=d($_); say if d($_+1)==$dk && d($_+2)==$dk && d($_+3)==$dk } # _Dana Jacobsen_, May 31 2015
%o A257892 (Perl) use ntheory ":all"; { my @prime; sub d { 2*$prime[$_[0]-1] - $prime[$_[0]] } sub list { my $n=shift; @prime=@{primes(nth_prime($n+5))}; my @d=map{d($_)}1..4; my @list; for (1..$n) { push @list,$_ if $d[0]==$d[1] && $d[0]==$d[2] && $d[0]==$d[3]; @d=(@d[1..3],d($_+4)) } @list; } } say join ", ",list(1e6); # _Dana Jacobsen_, May 31 2015
%o A257892 (Haskell)
%o A257892 a257892 n = a257892_list !! (n-1)
%o A257892 a257892_list = map a258432 $ filter ((== 4) . a258383) [1..]
%o A257892 -- _Reinhard Zumkeller_, May 31 2015
%Y A257892 Subsequence of A257762 and A062234.
%Y A257892 Cf. A258383, A258432, A258437, A258469, A258449, A257892, A257951.
%K A257892 nonn
%O A257892 1,1
%A A257892 _Zak Seidov_, May 14 2015