A050945 Numbers k such that sigma(k) > sigma(k+1) > sigma(k+2) > sigma(k+3) > sigma(k+4) > sigma(k+5).

20021154, 28503474, 53728674, 224539314, 242917674, 304178874, 341295954, 370845474, 377692314, 443998554, 533007474, 610484874, 709445274, 855529674, 964885074, 978052074, 1069943874, 1114988874, 1167961794

Offset

1,1

Comments

There are many examples of 4 consecutive numbers having decreasing values of sigma (see cross references) and there are 83 cases of 6 consecutive numbers with decreasing values of sigma < 4,293,000,000. Interestingly (and for unknown reasons) there are no examples of exactly 5 such consecutive numbers in that range! All known members of the sequence are multiples of 6 and one less than a multiple of 35.

References

David Wells, The Penguin Dictionary of Curious and Interesting Numbers, entry 44.

Links

Seiichi Manyama, Table of n, a(n) for n = 1..100

Example

sigma(20021154)=40894848 > sigma(20021155)=35458560 > ... > sigma(20021159)=20021160.

Crossrefs

Cf. A000203, A050944, A053226, A364657, A364680.

Sequence in context: A251513 A103123 A107618 * A251458 A116497 A346685

Adjacent sequences: A050942 A050943 A050944 * A050946 A050947 A050948

Keyword

nonn

Author

Jud McCranie, Jan 02 2000

Extensions

Name simplified by Seiichi Manyama, Aug 03 2023

Status

approved