The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A341982 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A341982

Number of ways to write n as an ordered sum of 2 primes (counting 1 as a prime).
(history; published version)

#14 by Alois P. Heinz at Fri Sep 16 21:44:59 EDT 2022

NAME

Number of ways to write n as an ordered sum of 2 non-composite numbersprimes (counting 1 as a prime).

KEYWORD

nonn,changed

nonn

EXTENSIONS

Better definition by J. Lowell, Sep 16 2022

STATUS

proposed

approved

#13 by J. Lowell at Fri Sep 16 21:44:46 EDT 2022

STATUS

editing

proposed

#12 by Alois P. Heinz at Fri Sep 16 21:41:37 EDT 2022

STATUS

proposed

editing

Discussion

Fri Sep 16

21:42

Alois P. Heinz: but you can count it as if it were a prime.  This is used in over 50 sequences.  Example: A001031.

21:43

Alois P. Heinz: don't try to make silly changes ... there are better things to do.

21:44

J. Lowell: Do you really think 1 can be considered a prime number for some purposes??

21:44

Alois P. Heinz: back to original ...

#11 by J. Lowell at Fri Sep 16 21:38:21 EDT 2022

STATUS

editing

proposed

#10 by J. Lowell at Fri Sep 16 21:37:47 EDT 2022

EXTENSIONS

Better definition by J. Lowell, Sep 16 2022

Discussion

Fri Sep 16

21:38

J. Lowell: 1 is not a prime number. We need to avoid considering it to be such when defining sequences.

#9 by J. Lowell at Fri Sep 16 21:37:32 EDT 2022

NAME

Number of ways to write n as an ordered sum of 2 primes (counting 1 as a prime)non-composite numbers.

STATUS

approved

editing

#8 by Alois P. Heinz at Thu Feb 25 15:27:07 EST 2021

STATUS

editing

approved

#7 by Alois P. Heinz at Thu Feb 25 15:27:05 EST 2021

LINKS

Alois P. Heinz, <a href="/A341982/b341982.txt">Table of n, a(n) for n = 2..10000</a>

STATUS

approved

editing

#6 by Alois P. Heinz at Wed Feb 24 21:49:52 EST 2021

STATUS

editing

approved

#5 by Alois P. Heinz at Wed Feb 24 21:49:50 EST 2021

MAPLE

b:= proc(n) option remember; series(`if`(n=0, 1, x*add(

`if`(j=1 or isprime(j), b(n-j), 0), j=1..n)), x, 3)

end:

a:= n-> coeff(b(n), x, 2):

seq(a(n), n=2..88); # Alois P. Heinz, Feb 24 2021

STATUS

proposed

editing