A373610 - OEIS

A373610

Positive integers that cannot be written as a sum of a practical number and an octagonal number.

11, 15, 34, 35, 47, 59, 103, 110, 115, 122, 123, 142, 146, 154, 159, 167, 179, 195, 203, 207, 214, 239, 247, 251, 262, 287, 290, 311, 318, 319, 323, 339, 354, 355, 362, 394, 434, 447, 466, 538, 542, 563, 599, 627, 682, 707, 718, 739, 743, 759, 774, 782, 867

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OFFSET

1,1

COMMENTS

Somu and Tran (2024) conjectured that there are finitely many such integers. It was also conjectured that 4005819 is the largest such integer. This conjecture was checked up to 10^8.

LINKS

Duc Van Khanh Tran, Table of n, a(n) for n = 1..414

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. A000567, A005153.

Sequence in context: A030099 A085597 A316643 * A097512 A032490 A068483

Adjacent sequences: A373607 A373608 A373609 * A373611 A373612 A373613

KEYWORD

nonn,hard

AUTHOR

Duc Van Khanh Tran, Jun 10 2024

STATUS

approved