A369558 a(n) is the minimum value of k > 0 such that A075860(n) = A075860(n+k) with n > 1.

2, 6, 4, 1, 6, 3, 7, 5, 10, 110, 6, 9, 13, 1, 10, 193, 6, 15, 1, 9, 22, 250, 1, 10, 6, 1, 5, 370, 8, 27, 7, 23, 34, 1, 6, 398, 2, 6, 9, 610, 4, 39, 13, 7, 2, 730, 6, 1, 1, 9, 3, 850, 11, 9, 6, 28, 58, 1586, 3, 57, 8, 13, 2, 7, 3, 818, 25, 5, 11, 1210, 5, 69, 1, 11

Offset

2,1

Links

Table of n, a(n) for n=2..75.

Example

For n=5, A075860(5) = A075860(5+1), so a(5)=1.
For n=15, A075860(15) = A075860(15+1), so a(15)=1.

Maple

f := proc(n) option remember;
    if isprime(n) then
        n;
    else
        procname(convert(numtheory:-factorset(n), `+`));
    fi;
end proc:
g := proc(n)
    local k;
    for k from 1 do
        if f(n+k) = f(n) then
            return k;
        fi;
    end do;
end proc:
map(g, [$2..100]);

Prog

(PARI) fp(n, pn) = if (n == pn, n, fp(vecsum(factor(n)[, 1]), n));
f(n) = if (n==1, 0, fp(n, 0));
a(n) = my(k=1, fn=f(n)); while(f(n+k) != fn, k++); k; \\ Michel Marcus, Feb 20 2024

Crossrefs

Cf. A075860.

Sequence in context: A059574 A332395 A004600 * A370673 A325497 A021795

Adjacent sequences: A369555 A369556 A369557 * A369559 A369560 A369561

Keyword

nonn

Author

Rafik Khalfi, Jan 25 2024

Status

approved