A382619 a(1) = 2; for n > 1, a(n) = a(n-1)*prime(n) if a(n-1)<=prime(n), otherwise a(n) = a(n-1)-prime(n).

2, 6, 1, 7, 77, 64, 47, 28, 5, 145, 114, 77, 36, 1548, 1501, 1448, 1389, 1328, 1261, 1190, 1117, 1038, 955, 866, 769, 668, 565, 458, 349, 236, 109, 14279, 14142, 14003, 13854, 13703, 13546, 13383, 13216, 13043, 12864, 12683, 12492, 12299, 12102, 11903

Offset

1,1

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Example

For n = 5, a(4)=7 and prime(5)=11, since a(4)<prime(5), a(5)=a(4)*prime(5)=77.
For n = 6, a(5)=77 and prime(6)=13, since a(5)>prime(6), a(6)=a(5)-prime(6)=64.

Mathematica

FoldList[If[# <= #2, #*#2, # - #2] &, Prime[Range[100]]] (* Paolo Xausa, Sep 15 2025 *)

Prog

(PARI) lista(nn) = my(v=vector(nn)); v[1] = 2; for (n=2, nn, if (v[n-1] <= prime(n), v[n] = v[n-1]*prime(n), v[n] = v[n-1]-prime(n)); ); v; \\ Michel Marcus, Apr 01 2025

Crossrefs

Cf. A387775.

Sequence in context: A201936 A019679 A387775 * A104457 A155832 A136764

Adjacent sequences: A382616 A382617 A382618 * A382620 A382621 A382622

Keyword

easy,look,nonn

Author

Anant Pratap Singh, Apr 01 2025

Status

approved