A377462 - OEIS

A377462

a(n) is the size of the central part of the symmetric representation of sigma(n), or 0 if such a part does not exits.

1, 3, 0, 7, 0, 12, 0, 15, 3, 0, 0, 28, 0, 0, 8, 31, 0, 39, 0, 42, 0, 0, 0, 60, 5, 0, 0, 56, 0, 72, 0, 63, 0, 0, 12, 91, 0, 0, 0, 90, 0, 96, 0, 0, 32, 0, 0, 124, 7, 15, 0, 0, 0, 120, 0, 120, 0, 0, 0, 168, 0, 0, 16, 127, 0, 144, 0, 0, 0, 36, 0, 195, 0, 0, 0, 0, 18, 0, 0, 186, 9, 0, 0, 224, 0

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OFFSET

1,2

COMMENTS

a(n) = A000203(n) if and only if n is a member of A174973.

LINKS

Table of n, a(n) for n=1..85.

EXAMPLE

For n = 9 the symmetric representation of sigma(9) = 13 in the first quadrant looks like this:

._ _ _ _ _ 5

|_ _ _ _ _|

. |_ _ 3

. |_ |

. |_|_ _ 5

. | |

. . . . . . . . |_| . . x

There are three parts [5, 3, 5] and the central part is 3 so a(9) = 3.

CROSSREFS

Indices of odd terms give A028982.

Indices of even terms give A028983.

Indices of zeros give A071561.

Indices of nonzero terms give A071562.

Nonzero terms give A295423.

Parity gives A053866.

Has the same parity as A000203, A000593, A001227, A033879, A033880, A067742.

Cf. A174973, A196020, A235791, A236104, A237270, A237271, A237591, A237593, A241558, A241559, A245092, A262626, A347950.

Sequence in context: A249904 A324875 A266437 * A077896 A359061 A238942

Adjacent sequences: A377456 A377457 A377460 * A377463 A377464 A377465

KEYWORD

nonn

AUTHOR

Omar E. Pol, Oct 29 2024

STATUS

approved