A374055 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A374055

a(1)=1, a(2)=4, and thereafter a(n) = a(n-2) + k * a(n-1), with minimal k >= 1 such that a(n) is not prime.

1, 4, 9, 22, 75, 172, 247, 666, 913, 2492, 3405, 9302, 12707, 22009, 34716, 56725, 91441, 148166, 239607, 387773, 627380, 1015153, 1642533, 2657686, 4300219, 6957905, 11258124, 18216029, 29474153, 47690182, 77164335, 124854517, 202018852, 326873369, 528892221

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..35.

EXAMPLE

For n=5, the smallest 9 + k*22 which is not prime is a(5) = 75 at k=3.

CROSSREFS

Cf. A018252, A072999.

Sequence in context: A231338 A257272 A370021 * A070713 A060250 A138991

Adjacent sequences: A374052 A374053 A374054 * A374056 A374057 A374058

KEYWORD

nonn

AUTHOR

Nicholas J. Leuchtenberg, Jun 26 2024

STATUS

approved