A164531 a(1)=1. a(n) = the smallest multiple of d(n) that is >= a(n-1), where d(n) = the number of positive divisors of n.

1, 2, 2, 3, 4, 4, 4, 4, 6, 8, 8, 12, 12, 12, 12, 15, 16, 18, 18, 18, 20, 20, 20, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 27, 28, 28, 28, 32, 32, 32, 32, 36, 36, 36, 36, 40, 42, 42, 44, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 49, 52, 56, 56, 60, 60, 64, 64, 72, 72

Offset

1,2

Links

John Tyler Rascoe, Table of n, a(n) for n = 1..10000

Mathematica

Block[{n = 1, d}, NestList[(d = DivisorSigma[0, ++n]) * Ceiling[# / d] &, 1, 100]] (* Paolo Xausa, Mar 21 2024 *)

Prog

(PARI)
A164531_list(nmax)={my(A=vector(nmax)); A[1]=1;
for(k=2, nmax, my(i=1); while(numdiv(k)*i<A[k-1], i+=1); A[k]=numdiv(k)*i); A}
A164531_list(100) \\ John Tyler Rascoe, Mar 20 2024

Crossrefs

Cf. A000005, A164530.

Sequence in context: A340619 A334800 A228942 * A138161 A307483 A034136

Adjacent sequences: A164528 A164529 A164530 * A164532 A164533 A164534

Keyword

nonn,easy

Author

Leroy Quet, Aug 15 2009

Extensions

Extended by Ray Chandler, Mar 15 2010

Status

approved