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A094178 Numbers n such that 4n+1 is divisible only by primes of form 4m+1 (i.e., by the Pythagorean primes A002144). 5

%I #16 Jul 28 2017 23:56:22

%S 1,3,4,6,7,9,10,13,15,16,18,21,22,24,25,27,28,31,34,36,37,39,42,43,45,

%T 46,48,49,51,55,57,58,60,64,66,67,69,70,72,73,76,78,79,81,84,87,88,91,

%U 93,94,97,99,100,102,105,106,108,111,112,114,115,120,121,123,126,127

%N Numbers n such that 4n+1 is divisible only by primes of form 4m+1 (i.e., by the Pythagorean primes A002144).

%C For the actual numbers 4n+1, see A008846(n).

%C Complement of A124934; A125203(a(n)) = 0; A000290 and A000217 are subsequences. - _Reinhard Zumkeller_, Nov 24 2006

%H Reinhard Zumkeller, <a href="/A094178/b094178.txt">Table of n, a(n) for n = 1..10000</a>

%o (Haskell)

%o import Data.List (elemIndices)

%o a094178 n = a094178_list !! (n-1)

%o a094178_list = map (+ 1) $ elemIndices 0 a125203_list

%o -- _Reinhard Zumkeller_, Jan 02 2013

%K nonn

%O 1,2

%A _Lekraj Beedassy_, May 06 2004

%E More terms from _Ray Chandler_, Jun 20 2004

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Last modified March 28 16:28 EDT 2024. Contains 371254 sequences. (Running on oeis4.)