A295042 Numbers k such that both k and (k+1) are abundant, and neither is divisible by 3.

55959128224, 68972878975, 91653987424, 171967420624, 350441716624, 372944997424, 386136575824, 711480344575, 769856312224, 789255692224, 818564922175, 997039218175, 1071710665024, 1216042052224, 1340586071824, 1925671372624, 1954925637664, 2045947528624

Offset

1,1

Comments

Subsequence of A096399.

All terms are of the form 3j+1, with j = 18653042741, 22990959658, 30551329141, 57322473541, 116813905541, 124314999141, 128712191941, 237160114858, 256618770741, 263085230741, 272854974058, 332346406058, ...

Links

David A. Corneth, Table of n, a(n) for n = 1..988 (first 87 terms from Giovanni Resta)

Example

k = 55959128224 is in the sequence as sigma(k) > 2*k and sigma(k + 1) > 2*(k + 1). - David A. Corneth, Apr 11 2021

Mathematica

abQ[n_] := Mod[n, 3] > 0 && DivisorSigma[1, n] > 2 n; abQ1[n_] := abQ[n - 1]; abQ2[n_] := abQ[n + 1]; s = Import["b115414.txt", "Data"][[All, -1]]; s1 = Select[s, abQ1] - 1; s2 = Select[s, abQ2]; seq = Union[s1, s2] (* using the b-File from A115414 *)

Prog

(PARI) isoka(n) = (n%3) && (sigma(n) > 2*n);
isok(n) = isoka(n) && isoka(n+1); \\ Michel Marcus, Nov 13 2017

Crossrefs

Cf. A005101, A096399, A115414.

Sequence in context: A273928 A344196 A346365 * A320880 A015401 A273930

Adjacent sequences: A295039 A295040 A295041 * A295043 A295044 A295045

Keyword

nonn

Author

Amiram Eldar, Nov 13 2017

Extensions

a(13)-a(18) from Giovanni Resta, Aug 22 2018

Status

approved