A122567 - OEIS

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A122567

Twin primes modulo 4.

3, 1, 3, 3, 1, 1, 3, 1, 3, 1, 3, 3, 1, 3, 1, 1, 3, 3, 1, 1, 3, 1, 3, 3, 1, 3, 1, 1, 3, 3, 1, 3, 1, 1, 3, 1, 3, 3, 1, 3, 1, 3, 1, 3, 1, 1, 3, 1, 3, 1, 3, 3, 1, 1, 3, 1, 3, 3, 1, 1, 3, 1, 3, 3, 1, 1, 3, 1, 3, 3, 1, 3, 1, 1, 3, 1, 3, 3, 1, 3, 1, 1, 3, 1, 3, 1, 3, 1, 3, 3, 1, 3, 1, 3, 1, 1, 3, 3, 1, 3, 1, 3, 1, 3, 1

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..105.

EXAMPLE

The twin primes are 3,5,7,11,13,17,19,... and mod 4 is 3,1,3,3,1,1,3...

MAPLE

a[1]:=3:i:=2:for k from 5 to 3000 do if isprime(k) and isprime(k+2) then a[i]:=k mod 4:a[i+1]:=k+2 mod 4: i:=i+2 fi od: seq(a[n], n=1..i-1);

CROSSREFS

Cf. A001097.

Sequence in context: A298262 A359525 A124814 * A122431 A279340 A089607

Adjacent sequences: A122564 A122565 A122566 * A122568 A122569 A122570

KEYWORD

nonn

AUTHOR

Miklos Kristof, Sep 21 2006

STATUS

approved