A086986 Numbers n such that sigma(n) can be represented as sum{i=0,k, sigma(m+i)}, with k>0.

3, 4, 7, 8, 9, 10, 12, 13, 16, 17, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 73, 75, 76, 77, 78, 81, 82, 83, 84, 85, 86, 87, 89

Offset

1,1

Comments

Is it true that every integer n ultimately has sigma(n) representable like this?

Links

Table of n, a(n) for n=1..71.

Example

sigma(61)=62=sigma(13)+sigma(14)+sigma(15)=14+24+24

Prog

(PARI) { s=vector(1000); sc=0; for (k=1, 10, for (i=1, 100, s[sc++ ]=sum(j=0, k, sigma(i+j)))); s=vecsort(s); s } for (i=2, 100, for (j=1, 1000, if (sigma(i)==s[j], print1(i", "); break)))

Crossrefs

Cf. A086987 gives values of sigma.

Sequence in context: A097044 A198330 A232779 * A346126 A057811 A284489

Adjacent sequences: A086983 A086984 A086985 * A086987 A086988 A086989

Keyword

nonn

Author

Jon Perry, Jul 27 2003

Status

approved