A083572 Smaller of two consecutive star numbers (A000567) whose sum is a square.

0, 1, 2296, 40833, 22847280, 395417121, 219458276136, 3797122504033, 2107246056196960, 36460001965365441, 20233777167801893976, 350088938217540957633, 194284726332034400465040, 3361553948612830233684961

Offset

1,3

Comments

The star numbers referred to here are those defined as the sum of the n-th square and four times the (n-1)st triangular number: 3n^2 - 2n.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..503

Example

a(2)=1 because
...
.*.
...
plus
..*...*...*...*
........*......
..*...........*
...*.........*.
..*...........*
........*......
..*...*...*...*
is
..*...*...*...*
........*......
..*...........*
...*....*....*.
..*...........*
........*......
..*...*...*...*

Prog

(PARI) list(lim)=my(x=0, y=1, v=List(), t); lim=sqrt(12*lim+4)/6+1/3; while(x<=lim, listput(v, x*(3*x-2)); t=49*x+20*y+8; y=120*x+49*y+20; x=t); x=1; y=3; while(x<=lim, listput(v, x*(3*x-2)); t=49*x+20*y+8; y=120*x+49*y+20; x=t); vecsort(Vec(v)) \\ Charles R Greathouse IV, Jul 24 2011

Crossrefs

Sequence in context: A306871 A123911 A126173 * A270854 A260292 A359321

Adjacent sequences: A083569 A083570 A083571 * A083573 A083574 A083575

Keyword

nonn

Author

Jason Earls, Jun 13 2003

Extensions

a(10)-a(12) from Donovan Johnson, May 24 2009

Offset corrected and a(13)-a(14) from Donovan Johnson, Jul 24 2011

Status

approved