A128690 -id:A128690 - cp's OEIS frontend

A128689 Numbers k such that A000118(k) is a record.

0, 1, 2, 3, 5, 6, 9, 10, 14, 18, 26, 30, 42, 54, 66, 78, 90, 114, 126, 150, 186, 198, 210, 270, 330, 378, 390, 450, 510, 546, 570, 630, 798, 810, 882, 930, 990, 1050, 1170, 1350, 1386, 1470, 1530, 1638, 1650, 1710, 1890, 2250, 2310, 2610, 2730, 2970, 3150, 3510, 3570

Offset: 1

Jonathan Vos Post, Mar 21 2007

nonn

This sequence is equivalent to numbers k such that sigma(k) > sigma(m) for all m < k where m and k are not multiples of 4 as no terms are multiples of 4 and A000118(n) = 8*sigma(n) for nonmultiples of 4. - David A. Corneth, May 19 2023

David A. Corneth, Table of n, a(n) for n = 1..392 (terms <= 10^8)

Cf. A000118 (number of ways of writing n as a sum of 4 squares), A002093, A042968 A128690.

f[n_] := SquaresR[4, n];
Module[{record = -1, n}, Reap[For[n = 0, n <= 2000, n++, If[f[n] > record, record = f[n]; Sow[n]]]][[2, 1]]] (* Jean-François Alcover, May 18 2023 *)
DeleteDuplicates[Table[{n,SquaresR[4,n]},{n,0,3600}],GreaterEqual[#1[[2]],#2[[2]]]&][[;;,1]] (* Harvey P. Dale, Jun 20 2024 *)

Missing term 378 added by Giovanni Resta, Jun 18 2016
More terms from Jean-François Alcover, May 18 2023
More terms from David A. Corneth, May 18 2023

cp's OEIS Frontend

A128689 Numbers k such that A000118(k) is a record.

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