A347568 - OEIS

A347568

Positive integers which are not twice a positive triangular number and cannot be written as twice a positive triangular number plus an odd prime or twice a positive triangular number plus twice an odd prime.

1, 3, 4, 10, 14, 122, 422, 432

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OFFSET

1,2

COMMENTS

Probably finite. No more terms < 10^9.

Asked by an anonymous person on Wikipedia, December 31 2021.

No more terms < 10^11. - Martin Ehrenstein, Jan 15 2022

LINKS

Table of n, a(n) for n=1..8.

Wikipedia:Reference desk/Mathematics, Original question on Wikipedia December 31 2021

EXAMPLE

5 is NOT a term because 5 is not twice a triangular number and it can be written as 2*1+3, where 1 is a triangular and 3 is an odd prime. However, 10 is a term because it cannot be written in this way.

CROSSREFS

Cf. A000040, A000217, A347567.

Sequence in context: A056517 A285042 A319719 * A048155 A242342 A204292

Adjacent sequences: A347565 A347566 A347567 * A347569 A347570 A347571

KEYWORD

nonn,more

AUTHOR

Jud McCranie, Jan 02 2022

STATUS

approved