|
| |
|
|
A078667
|
|
Integers that occur more than once as as the difference [p_n]^2 - [p_(n-1)]^2 of the squares of two consecutive primes.
|
|
7
| |
|
|
72, 120, 168, 312, 408, 552, 600, 768, 792, 912, 1032, 1848, 1848, 2472, 3048, 3192, 3288, 3528, 3720, 4008, 4920, 4920, 4920, 5160, 5208, 5808, 5928, 6072, 6480, 6792, 6840, 6888, 6888, 7080, 7152, 7248, 7512, 7728, 7800, 8520, 8760, 9072, 11400
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
EXAMPLE
| 120=31^2-29^2=17^2-13^2
|
|
|
PROG
| (PARI) pv(v)=vecsort(vecextract(v, concat("1..", vc-1))) op=2; v=vector(5000); vc=1; forprime (p=3, 5000, v[vc]=p^2-op^2; vc++; op=p) v=pv(v) for (i=2, length(v), if (v[i]==v[i-1], print1(v[i]", ")))
(PARI) pv(v)=vecsort(vecextract(v, concat("1..", vc-1))) op=2; v=vector(5000); vc=1; forprime (p=3, 5000, v[vc]= p^2-op^2; vc++; op=p) v=pv(v) for (i=2, length(v), if (v[i]==v[i-1], print1(v[i]", ")))
|
|
|
CROSSREFS
| Cf. A090783, A090784, A090785, A091878.
Sequence in context: A143610 A166987 A169644 * A090784 A143741 A157336
Adjacent sequences: A078664 A078665 A078666 * A078668 A078669 A078670
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Jon Perry (perry(AT)globalnet.co.uk), Dec 15 2002
|
| |
|
|
