A364680 -id:A364680 - cp's OEIS frontend

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

Jud McCranie, Jan 02 2000

nonn

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.

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

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

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

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

Name simplified by Seiichi Manyama, Aug 03 2023

A364704 Smallest initial number k of n consecutive numbers satisfying sigma(k) < sigma(k+1) < ... < sigma(k+n-1).

Original entry on oeis.org

1, 1, 1, 1, 36721681, 36721681

Offset: 1

Seiichi Manyama, Aug 03 2023

a(7) > 5*10^10. (Calculated using the b-file in A028965.)

Cf. A000203, A075028, A285893, A364680.

Cf. A028965, A053224, A364659, A364662.

PARI
```
b(n) = my(k=n); while(sigma(k)
				
```

cp's OEIS Frontend

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

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