login
A307187
Numbers k such that A095112(k)/k sets a new record.
2
1, 2, 4, 6, 8, 12, 24, 48, 60, 120, 240, 360, 720, 1440, 1680, 2520, 5040, 10080, 15120, 20160, 30240, 50400, 55440, 110880, 166320, 221760, 332640, 665280, 1108800, 1330560, 1441440, 1663200, 2882880, 3326400, 4324320, 7207200, 8648640, 14414400, 17297280
OFFSET
1,2
COMMENTS
k is in the sequence iff k is in position k in row k of A307081; in other words, iff A307088(k) = k.
EXAMPLE
With f(k) = A095112(k)/k,
f(1) = 0, new record, so 1 is in the sequence;
f(2) = 1/2, new record, so 2 is in the sequence;
f(3) = 1/3;
f(4) = 1/2 + 1/4 = 3/4, new record, so 4 is in the sequence;
f(5) = 1/5;
f(6) = 1/2 + 1/3 = 5/6, new record, so 6 is in the sequence;
etc.
PROG
(PARI)
f(n)={my(s=0, T); T=factorint(n); for(i=1, #T[, 1], for(j=1, T[i, 2], s+=1/T[i, 1]^j)); s}
prog(n)={my(V, v, j); V=List(); for(k=1, n, v=f(k)+0.; j=setsearch(V, v, 1); if(j==k, print1(k, ", ")); if(j==0, print("err"); return, listinsert(V, v, j)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Luc Rousseau, Mar 28 2019
STATUS
approved