A387741 Positive integers that cannot be represented as the sum plus product of a multiset of at least two integers greater than 1.

1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 13, 16, 18, 21, 22, 25, 28, 30, 37, 45, 52, 57, 58, 70, 81, 100, 102, 108, 130, 133, 148, 157, 162, 193, 225, 253, 262, 273, 325, 430, 477, 508, 613, 652, 682, 1821

Offset

1,2

Comments

An excellent sequence to explore with elementary school students learning multiplication.

Links

Table of n, a(n) for n=1..46.

Example

To see why 33 is not listed consider the multiset {2,2,2,3}. (2+2+2+3) + (2*2*2*3) = 33.
34 is also not listed because of the multiset {2,2,6}. (2+2+6) + (2*2*6) = 34.
There is no such multiset for 37. That is why it is listed.

Crossrefs

A254636 is similar except that it limits the sets to two elements.

Sequence in context: A190278 A372477 A254636 * A165763 A178877 A011870

Adjacent sequences: A387738 A387739 A387740 * A387742 A387743 A387744

Keyword

nonn,more

Author

Gordon Hamilton, Sep 06 2025

Extensions

More terms from Alois P. Heinz, Sep 06 2025

Status

approved