|
|
A189475
|
|
First differences of A036449, triangular numbers by definition.
|
|
3
|
|
|
1, 3, 21, 171, 1485, 435, 16653, 149331, 1342341, 12076155, 990528, 1279200, 263901, 169071, 446985, 133865703, 1180416, 1214185281, 2366400, 25045503, 247275441, 8923200, 19634511, 56525028, 229847520, 739374285, 224497455, 81939201, 24010841091, 1106357280
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
FORMULA
|
|
|
PROG
|
(Haskell) Cf. program in A036449 (simultaneous computation).
(Python)
from itertools import count, islice
from sympy import integer_nthroot
def A189475_gen(): # generator of terms
a = 0
for n in count(1):
if integer_nthroot(((b:=n**2)-a<<3)+1, 2)[1]:
yield b-a
a = b
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|