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A100672 Second least-significant bit in the binary expansion of the k-th prime. +0
3
1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1 (list; graph; listen)
OFFSET

1,1

COMMENT

a(n)=1 iff Prime[n] is a member of A045326 (equivalently, iff Prime[n]-3 is divisible by 4)

LINKS

Eric Weisstein's World of Mathematics, Fermat's 4n Plus 1 Theorem.

Eric Weisstein's World of Mathematics, Gaussian Prime.

FORMULA

a(n) := Mod[Prime[n], 4] != 2

EXAMPLE

a(2)=1 because Prime[2]=11_2 (in binary; decimal = 3_10) and its 2^1 bit is 1.

a(3)=0 because Prime[3]=101_2 (in binary; decimal = 5_10) and its 2^1 bit is 0.

MATHEMATICA

Table[Reverse[RealDigits[Prime[k], 2][[1]]][[2]], {k, 1, 128}]

CROSSREFS

Cf. A045326.

Cf. A002144, A002145.

equal to 1 minus A098033 [From Steven G. Johnson (stevenj(AT)math.mit.edu), Sep 18 2008]

Sequence in context: A123594 A145006 A080813 this_sequence A079559 A014577 A157926

Adjacent sequences: A100669 A100670 A100671 this_sequence A100673 A100674 A100675

KEYWORD

base,nonn

AUTHOR

Joseph Biberstine (jrbibers(AT)indiana.edu), Dec 06 2004

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Last modified November 29 12:46 EST 2009. Contains 167659 sequences.


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