A258968 a(n) is the least positive integer x with A054973(x) = n and A258913(x) < x.

2, 3, 124, 10714158

Offset

0,1

Comments

Is a(n) well-defined for all n?

For n > 1, a(n) belongs to sequence A258931.

The terms a(k), for 4 <= k <= 100, if they exist, are larger than 3*10^10. - Giovanni Resta, Jun 15 2015

Links

Table of n, a(n) for n=0..3.

Example

For n=2, sigma(x)=124 for x=48 and 75, and 48+75 = 123 < 124.
For n=3, sigma(x)=10714158 for x=3031200, 3417300, and 3987450; and their sum is 10435950 (<10714158).

Prog

(PARI) a(n)=x=0; while(x++, u=List(); for(i=1, x, if(sigma(i)==x, listput(u, i))); if(#u==n&vecsum(Vec(u))<x, return(x))) \\ not optimized because the same sigma values are calculated over and over again instead of being kept

Crossrefs

Cf. A054973, A258913, A258931, A007368, A258914.

Sequence in context: A051177 A371271 A334661 * A125674 A180533 A095841

Adjacent sequences: A258965 A258966 A258967 * A258969 A258970 A258971

Keyword

nonn,more

Author

Jeppe Stig Nielsen, Jun 15 2015

Status

approved