login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A342824 Number of ways n appears as a cross-polytope number (A142978). 0
1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 3, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 2, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 2, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,3

COMMENTS

Every entry in the first column (of A142978) is 1, so this sequence starts at a(2).

a(n) is always positive, as the first row lists the positive integers.

a(n) >= 3 infinitely often. This happens, in particular, at every even square > 4. (The second row contains the squares, and the second column the positive even numbers.)

For n <= 10000, the only instance of a(n) > 3 is a(1156) = 4. This occurs because 1156 is even, square, and octahedral (third row of A142978).

LINKS

Table of n, a(n) for n=2..88.

PROG

(Sage) def a(n) : return len([K for K in [2..n] if n == next(A142978(N, K) for N in (1..) if A142978(N, K) >= n)])

CROSSREFS

Cf. A142978.

Sequence in context: A071854 A183025 A072410 * A072491 A051034 A024935

Adjacent sequences:  A342821 A342822 A342823 * A342825 A342826 A342827

KEYWORD

nonn

AUTHOR

Eric M. Schmidt, Mar 22 2021

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 8 18:28 EDT 2021. Contains 343666 sequences. (Running on oeis4.)