# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a333041 Showing 1-1 of 1 %I A333041 #11 Apr 14 2020 16:01:06 %S A333041 3,63,75,135,147,195,255,315,399,405,459,483,495,525,555,567,615,627, %T A333041 663,675,693,735,759,765,795,819,855,915,945,975,999,1035,1095,1125, %U A333041 1155,1215,1239,1287,1323,1395,1455,1515,1539,1575,1647,1659,1683,1755,1785,1815,1827,1845,1875 %N A333041 Odd numbers m such that sigma(m) > sigma(m-1). %C A333041 The odd terms of A333038 [sigma(m) <= sigma(m-1)] represent about 95% of the data, so the odd integers that do not satisfy this relation are proposed here. %C A333041 Except for 3, there are no prime powers in this sequence. %C A333041 It appears that most of the terms are divisible by 3; the two smallest exceptions are 13475 and 17255 (see A323726). %C A333041 Odd (and even) numbers such that sigma(m) = sigma(m-1) are in A231546. %e A333041 sigma(63) = 1+3+7+9+21+63 = 104 > sigma(62) = 1+2+31+62=96 and 63 is in the sequence. %e A333041 sigma(77) = 1+7+11+77 = 96 < sigma(76) = 1+2+4+19+38+76 = 140 and 77 is not a term. %t A333041 Select[2 * Range[1000] + 1, DivisorSigma[1, #] > DivisorSigma[1, # - 1] &] (* _Amiram Eldar_, Apr 14 2020 *) %o A333041 (PARI) is(n)=n%2 && sigma(n)>sigma(n-1) \\ _Charles R Greathouse IV_, Apr 14 2020 %Y A333041 A323726 is a subsequence. %Y A333041 Apart from the first term, a subsequence of A334117. %Y A333041 Cf. A000203, A053222, A231546, A333038, A333039, A333040. %K A333041 nonn %O A333041 1,1 %A A333041 _Bernard Schott_, Apr 14 2020 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE