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.
%I A163619 #13 Dec 03 2024 12:25:52 %S A163619 2,8,9,20,32,98,125,128,169,464,512,729,961,1280,2048,2108,5252,8000, %T A163619 8192,9728,15872,16807,18176,22385,32768,36992,50000,53792,59049, %U A163619 78821,81920,97556,98125,100352,124659,131072,195129,219488,223040,307328 %N A163619 Let q(p) be the smallest prime greater than the prime p. A positive integer n is included in this sequence if n+1 is divisible by q(p) for each prime p dividing n. %C A163619 All terms of this sequence are in sequence A073606. %C A163619 From _Robert Israel_, Dec 01 2024: (Start) %C A163619 If k is a term, then so is k^j for all odd j. %C A163619 If A226295(k) is even, then prime(k)^(A226295(k)/2) is a term. (End) %e A163619 20 is divisible by the primes 2 and 5. q(2) = 3, and q(5)=7. 20+1 = 21 is divisible by both 3 and 7, so 20 is in this sequence. %p A163619 filter:= n -> %p A163619 andmap(p -> n+1 mod nextprime(p) = 0, numtheory:-factorset(n)): %p A163619 select(filter, [$2..4*10^5]); # _Robert Israel_, Dec 01 2024 %t A163619 depQ[n_]:=With[{c=NextPrime[FactorInteger[n][[;;,1]]]},AllTrue[(n+1)/c,IntegerQ]]; Select[Range[ 2,350000],depQ] (* _Harvey P. Dale_, Jun 10 2023 *) %Y A163619 Cf. A073606, A226295. %K A163619 nonn %O A163619 1,1 %A A163619 _Leroy Quet_, Aug 01 2009 %E A163619 More terms from _Sean A. Irvine_, Oct 04 2009