A290490 Numbers k such that (sum of proper unitary divisors of k) > (sum of proper unitary divisors of m) for all m < k.

1, 2, 6, 10, 14, 18, 22, 26, 30, 42, 60, 66, 78, 102, 114, 138, 150, 174, 186, 210, 330, 390, 462, 510, 546, 570, 690, 798, 858, 870, 930, 1050, 1110, 1218, 1230, 1290, 1410, 1470, 1590, 1722, 1770, 1830, 2010, 2130, 2190, 2310, 2730, 3570, 3990, 4290, 4830, 5610, 6006, 6090, 6510, 7410, 7590, 7770

Offset: 1

Author

Ilya Gutkovskiy, Aug 03 2017

Keywords

• nonn

Comments

Numbers k such that A034460(k) > A034460(m) for all m < k.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1000
• Eric Weisstein's World of Mathematics, Unitary Divisor
• Index entries for sequences related to sums of divisors

Crossrefs

Cf. A002182, A002093, A034090, A034448, A034460, A063919, A280013, A281782, A285614.

Programs

Mathematica

mx = -1; t = {}; Do[u = DivisorSum[n, # &, GCD[#, n/#] == 1 &] - n; If[u > mx, mx = u; AppendTo[t, n]], {n, 8000}]; t

PARI

sumud(n) = sumdiv(n, d, if (gcd(d, n/d)==1, d)) - n;
lista(nn) = {lasts = -1; for (n=1, nn, if ((news = sumud(n)) > lasts, print1(n, ", "); lasts = news););} \\ Michel Marcus, Aug 04 2017