A374416 - OEIS

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A374416

a(n) is the number of ways n can be written as a sum of a practical number and two nonagonal numbers.

1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 2, 2, 2, 2, 1, 2, 2, 3, 2, 3, 2, 3, 0, 2, 3, 5, 2, 3, 3, 5, 2, 3, 3, 4, 1, 3, 4, 3, 2, 3, 4, 5, 2, 2, 3, 2, 1, 5, 6, 5, 3, 4, 3, 5, 3, 5, 5, 4, 2, 4, 4, 2, 4, 5, 5, 7, 4, 2, 2, 2, 3, 5, 5, 5, 4, 5, 3, 7, 5, 5

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OFFSET

1,2

COMMENTS

Somu and Tran (2024) proved that a(n) > 0 for sufficiently large n.

Conjecture (checked up to 10^8): a(n) = 0 if and only if n = 23.

LINKS

Duc Van Khanh Tran, Table of n, a(n) for n = 1..10000

Sai Teja Somu and Duc Van Khanh Tran, On sums of practical numbers and polygonal numbers, Journal of Integer Sequences, 27(5), 2024.

CROSSREFS

Cf. A001106, A005153.

Sequence in context: A375582 A280314 A080354 * A238529 A374415 A195150

Adjacent sequences: A374413 A374414 A374415 * A374417 A374418 A374419

KEYWORD

nonn

AUTHOR

Duc Van Khanh Tran, Jul 08 2024

STATUS

approved