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A046921 Number of ways to express 2n+1 as p+2a^2; p = 1 or prime, a >= 0. 7
1, 2, 2, 2, 2, 2, 3, 2, 1, 4, 3, 2, 3, 1, 2, 4, 2, 2, 4, 3, 2, 3, 3, 2, 4, 3, 2, 5, 1, 2, 6, 3, 1, 3, 4, 2, 5, 4, 2, 6, 3, 2, 4, 2, 3, 6, 2, 1, 4, 3, 4, 6, 4, 2, 6, 5, 2, 6, 3, 2, 5, 1, 2, 3, 5, 4, 5, 4, 1, 8, 4, 1, 6, 3, 2, 6, 2, 2, 6, 6, 1, 4, 5, 3, 7, 4, 3, 6, 2, 3, 10, 2, 3, 4, 4, 3, 3, 4, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Goldbach conjectured this sequence is never zero.

The only zero terms appear to be for the odd numbers 5777 and 5993. - T. D. Noe, Aug 23 2008

a(n) = A046920(A005408(n)). - Reinhard Zumkeller, Apr 03 2013

LINKS

T. D. Noe, Table of n, a(n) for n = 0..10000

L. Hodges, A lesser-known Goldbach conjecture, Math. Mag., 66 (1993), 45-47.

Index entries for sequences related to Goldbach conjecture

PROG

(Haskell)

a046921 = a046920 . a005408  -- Reinhard Zumkeller, Apr 03 2013

CROSSREFS

Cf. A042978, A046920, A046922, A046923, A060003, A143539.

Cf. A007697.

Sequence in context: A190617 A068323 A054990 * A262954 A262813 A188794

Adjacent sequences:  A046918 A046919 A046920 * A046922 A046923 A046924

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified July 21 21:14 EDT 2019. Contains 325199 sequences. (Running on oeis4.)