The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A000415 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A000415

Numbers that are the sum of 2 but no fewer nonzero squares.
(history; published version)

#46 by Michel Marcus at Tue Aug 01 12:03:19 EDT 2023

STATUS

reviewed

approved

#45 by Joerg Arndt at Tue Aug 01 11:53:38 EDT 2023

STATUS

proposed

reviewed

#44 by Michel Marcus at Tue Aug 01 10:00:30 EDT 2023

STATUS

editing

proposed

#43 by Michel Marcus at Tue Aug 01 10:00:26 EDT 2023

REFERENCES

E. Grosswald, E.; Representation of Integers as Sums of Squares, Springer-Verlag, New York Inc., (1985), p.15. - Ant King, Nov 02 2010

STATUS

proposed

editing

#42 by Chai Wah Wu at Tue Aug 01 09:55:25 EDT 2023

STATUS

editing

proposed

#41 by Chai Wah Wu at Tue Aug 01 09:55:18 EDT 2023

PROG

(Python)

from itertools import count, islice

from sympy import factorint

def A000415_gen(startvalue=2): # generator of terms >= startvalue

for n in count(max(startvalue, 2)):

f = factorint(n).items()

if any(e&1 for p, e in f if p&3<3) and not any(e&1 for p, e in f if p&3==3):

yield n

A000415_list = list(islice(A000415_gen(), 20)) # Chai Wah Wu, Aug 01 2023

STATUS

approved

editing

#40 by Alois P. Heinz at Sat Jul 16 16:33:08 EDT 2022

STATUS

editing

approved

#39 by Alois P. Heinz at Sat Jul 16 16:32:48 EDT 2022

FORMULA

Equals { A000404- } minus { A134422 }. - Artur Jasinski, Oct 25 2007

STATUS

approved

editing

Discussion

Sat Jul 16

16:33

Alois P. Heinz: setminus ... not -

#38 by Michael De Vlieger at Wed Jun 01 14:45:36 EDT 2022

STATUS

reviewed

approved

#37 by Michel Marcus at Wed Jun 01 14:00:50 EDT 2022

STATUS

proposed

reviewed