A123079 Twin primes of form 4k+1.

5, 13, 17, 29, 41, 61, 73, 101, 109, 137, 149, 181, 193, 197, 229, 241, 269, 281, 313, 349, 421, 433, 461, 521, 569, 601, 617, 641, 661, 809, 821, 829, 857, 881, 1021, 1033, 1049, 1061, 1093, 1153, 1229, 1277, 1289, 1301, 1321, 1429, 1453, 1481, 1489, 1609

Offset

1,1

Links

Table of n, a(n) for n=1..50.

Maple

a[1]:=5:i:=2:for k from 6 to 3000 do if isprime(k) and isprime(k+2) then b:=k:c:=k+2: if b mod 4 = 1 then a[i]:=b:i:=i+1 fi: if c mod 4 = 1 then a[i]:=c:i:=i+1 fi:fi od: seq(a[n], n=1..i-1);

Mathematica

Select[Union[Flatten[Select[Partition[Prime[Range[300]], 2, 1], #[[2]]-#[[1]]==2&]]], Mod[ #, 4]==1&] (* Harvey P. Dale, Oct 16 2022 *)

Crossrefs

Cf. A122564, A122565, A001097.

Sequence in context: A145016 A372078 A354155 * A273950 A268511 A038938

Adjacent sequences: A123076 A123077 A123078 * A123080 A123081 A123082

Keyword

nonn

Author

Miklos Kristof, Sep 27 2006

Status

approved