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A108546 Lexicographically earliest permutation of primes such that for n>1 forms 4*k+1 and 4*k+3 alternate. 7
2, 3, 5, 7, 13, 11, 17, 19, 29, 23, 37, 31, 41, 43, 53, 47, 61, 59, 73, 67, 89, 71, 97, 79, 101, 83, 109, 103, 113, 107, 137, 127, 149, 131, 157, 139, 173, 151, 181, 163, 193, 167, 197, 179, 229, 191, 233, 199, 241, 211, 257, 223, 269, 227, 277, 239, 281, 251, 293 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) mod 4 = 3 - 2 * (n mod 2) for n>1.

For n > 1: a(n) = A111745(n-1);

a(2*n+1) - a(2*n) = A102261(n).

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

MATHEMATICA

terms = 60; A111745 = Module[{prs = Prime[Range[2terms]], m3, m1, min}, m3 = Select[prs, Mod[#, 4] == 3&]; m1 = Select[prs, Mod[#, 4] == 1&]; min = Min[Length[m1], Length[m3]]; Riffle[Take[m3, min], Take[m1, min]]]; a[1] = 2; a[n_] := A111745[[n-1]]; Table[a[n], {n, 1, terms}] (* Jean-Fran├žois Alcover, May 18 2017, using Harvey P. Dale's code for A111745 *)

PROG

(Haskell)

import Data.List (transpose)

a108546 n = a108546_list !! (n-1)

a108546_list =  2 : concat

   (transpose [a002145_list, a002144_list])

-- Reinhard Zumkeller, Nov 13 2014, Feb 22 2011

CROSSREFS

Cf. A002144, A002145.

Sequence in context: A126055 A126054 A067836 * A065107 A185956 A316885

Adjacent sequences:  A108543 A108544 A108545 * A108547 A108548 A108549

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jun 10 2005

STATUS

approved

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Last modified November 17 15:57 EST 2019. Contains 329235 sequences. (Running on oeis4.)