A359852 a(n) is the smallest Fibonacci n-step number with exactly n distinct prime factors.

21, 504, 39648, 6930, 12669125245488, 471771076278370, 32818036405994618064, 71577732779401085355729600, 204945946670840805166309694624676331385919836360545974559162291811394735721440

Offset

2,1

Links

Table of n, a(n) for n=2..10.

Eric Weisstein's World of Mathematics, Distinct Prime Factors

Eric Weisstein's World of Mathematics, Fibonacci n-Step Number

Example

a(3) = 504, because 504 is a tribonacci number with 3 distinct prime factors {2, 3, 7} and this is the smallest such number.

Prog

(PARI) a(n) = my(v=vector(n+1), x=1, y=n+1); v[1]=v[y]=1; while(omega(v[x])!=n, y=x; x=x%(n+1)+1; v[x]=2*v[y]-v[x]); v[x]; \\ Jinyuan Wang, Jan 16 2023

Crossrefs

Cf. A001221, A060319, A359848, A359849, A359853.

Sequence in context: A231542 A065921 A129993 * A209348 A095655 A221766

Adjacent sequences: A359849 A359850 A359851 * A359853 A359854 A359855

Keyword

nonn

Author

Ilya Gutkovskiy, Jan 15 2023

Extensions

a(10) from Jinyuan Wang, Jan 16 2023

Status

approved