|
|
A359090
|
|
a(n) is the index of the smallest tetrahedral number with exactly n prime factors (counted with multiplicity), or -1 if no such number exists.
|
|
1
|
|
|
1, -1, 2, 4, 6, 8, 14, 30, 48, 62, 126, 160, 350, 510, 1022, 2046, 1024, 4095, 4094, 13310, 28672, 32768, 65534, 180224, 262142, 360448, 262143, 2097151, 3276800, 4194302, 2097150, 33554432, 16777214, 66715648, 33554430
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
LINKS
|
|
|
PROG
|
(PARI) a(n) = if(n==1, return(-1)); for(k=1, oo, my(t=(k*(k+1)*(k+2))\6); if(bigomega(t) == n, return(k))); \\ Daniel Suteu, Dec 30 2022
|
|
CROSSREFS
|
|
|
KEYWORD
|
sign,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|