The On-Line Encyclopedia of Integer Sequences (OEIS)

A093124 revision #13

A093124

a(n) is the least k such that Sum_{i=n-k..n} sigma(i) >= a(n-1).

1, 3, 4, 7, 13, 18, 20, 23, 28, 31, 43, 58, 72, 78, 90, 93, 97, 112, 132, 150, 151, 169, 193, 194, 225, 225, 233, 253, 259, 271, 272, 293, 301, 355, 403, 408, 446, 506, 562, 580, 590, 623, 667, 703, 727, 751, 799, 832, 851, 884, 900, 908, 920, 944, 972, 1008, 1010, 1028, 1040

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Is this sequence defined?

LINKS

Table of n, a(n) for n=1..59.

EXAMPLE

a(1) to a(4) are sigma(n) as these increase: 1 3 4 7. sigma(5)=6 and as this decreases, we examine sigma(5)+sigma(4)=7+6=13.

PROG

(PARI) lista(nn) = my(v=vector(nn)); v[1]=sigma(1); for (i=2, nn, k=0; while (sum(j=i-k, i, sigma(j))<v[i-1], k++); v[i]=sum(j=i-k, i, sigma(j))); v; \\ edited by Michel Marcus, Dec 28 2022

CROSSREFS

Cf. A000203, A093125.

Sequence in context: A076784 A279815 A088764 * A055664 A089374 A029552

Adjacent sequences: A093121 A093122 A093123 * A093125 A093126 A093127

KEYWORD

nonn

AUTHOR

Jon Perry, Mar 22 2004

EXTENSIONS

Name edited by and more terms from Michel Marcus, Dec 28 2022

STATUS

editing