cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A375160 Square array T(n, k), n >= 2 and k >= 1, read by antidiagonals in ascending order, give the smallest number that starts a sequence of exactly k consecutive numbers each having exactly n prime factors (counted with multiplicity), or -1 if no such number exists.

This page as a plain text file.
%I A375160 #37 Aug 11 2024 14:18:34
%S A375160 4,8,9,16,27,33,32,135,170,-1,64,944,1274,603,-1,128,5264,15470,4023,
%T A375160 602,-1,256,29888,33614,57967,12122,2522,-1,512,50624,3145310,8706123,
%U A375160 632148,204323,211673,-1
%N A375160 Square array T(n, k), n >= 2 and k >= 1, read by antidiagonals in ascending order, give the smallest number that starts a sequence of exactly k consecutive numbers each having exactly n prime factors (counted with multiplicity), or -1 if no such number exists.
%C A375160 All positive terms are composite.
%e A375160 T(2,3) = 33 = 3*11, because both 34 and 35 have the same number of prime factors. Thus, 33 is the starting number of a run of 3 numbers that each have 2 prime factors (counted with multiplicity). No lesser number has this property, so T(2,3) = 33.
%e A375160 Table begins (upper left corner = T(2,1)):
%e A375160    4        9       33      -1 ...
%e A375160    8       27      170     603 ...
%e A375160   16      135     1274    4023 ...
%e A375160   32      944    15470   57967 ...
%e A375160   ...     ...      ...     ... ...
%Y A375160 Cf. A002808, A062502.
%Y A375160 Cf. Numbers m through m+k have the same number of prime divisors (with multiplicity): A045920 (k=1), A045939 (k=2), A045940 (k=3), A045941 (k=4), A045942 (k=5), A123103 (k=6), A123201 (k=7), A358017 (k=8), A358018 (k=9), A358019 (k=10).
%K A375160 sign,tabl,more
%O A375160 2,1
%A A375160 _Jean-Marc Rebert_, Aug 09 2024