|
|
A175897
|
|
Numbers n with property that n*prime(n)+(n+1)*prime(n+1) is a perfect square s^2.
|
|
1
|
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
EXAMPLE
|
{n,s}: {1681,6943},{3146,13487},{5917,26299},{308950,1647737}, {10553441,63320647},{10553550,63321299}; no more n's up to 2*10^8.
|
|
MATHEMATICA
|
Position[Total/@Partition[Table[n Prime[n], {n, 310000}], 2, 1], _? (IntegerQ[ Sqrt[#]]&)]//Flatten (* The program generates the first four terms of the sequence. To generate more, Increase the Range constant, but the program may take a long time to run. *) (* Harvey P. Dale, Feb 05 2022 *)
|
|
PROG
|
(PARI) isok(n) = issquare(n*prime(n)+(n+1)*prime(n+1)); \\ Michel Marcus, Oct 19 2013
|
|
CROSSREFS
|
|
|
KEYWORD
|
more,nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|