login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A207973 Primes p such that the equation prime(p-k)+k! = prime(p) has at least one solution k>0. 0
2, 31, 43, 67, 107, 151, 167, 179, 227, 233, 389, 509, 547, 661, 719, 769, 823, 829, 967, 1033, 1093, 1259, 1321, 1493, 1567, 1733, 1873, 2099, 2341, 2539, 2621, 2683, 2819, 2927, 3119, 3169, 3373 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Apart from the first entry, the majority of the entries stem from k=4, i.e., this is essentially a reverse lookup within A033560. - R. J. Mathar, Mar 15 2012

LINKS

Table of n, a(n) for n=1..37.

EXAMPLE

2 is in the sequence because prime(2) = prime(2-1)+1 = 3,

31 is in the sequence because prime(31) = prime(31-4)+1*2*3*4 = 103+24 = 127,

43 is in the sequence because prime(43) = prime(43-4)+1*2*3*4 = 167+24 = 191.

PROG

(PARI) is_A207973(n)={local(k); k=1; while((k<n)&&(prime(n-k)+k!)<prime(n), k=k+1); if((k<n)&&(prime(n-k)+k!)==prime(n), isprime(n), 0)} /* Michael B. Porter, Mar 22 2012 */

CROSSREFS

Cf. A000040, A000142.

Sequence in context: A215031 A120638 A101017 * A193423 A241484 A235477

Adjacent sequences:  A207970 A207971 A207972 * A207974 A207975 A207976

KEYWORD

nonn

AUTHOR

Gerasimov Sergey, Mar 02 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 13 06:26 EST 2019. Contains 329968 sequences. (Running on oeis4.)