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%I #27 Sep 08 2022 08:46:20
%S 6,10,12,14,20,22,24,26,28,30,34,38,40,42,44,46,48,52,54,56,58,60,62,
%T 66,68,70,74,76,78,80,82,84,86,88,90,92,94,96,102,104,106,108,110,112,
%U 114,116,118,120,122,124,126,130,132,134,136,138,140,142,146,148
%N Numbers n > 1 such that n and sigma(n) have the same smallest prime factor.
%C Supersequence of A088829; this sequence contains also odd numbers: 441, 1521, 3249, 3969, 8649, 11025, ...
%C Even terms of A000396 (perfect numbers) are a subsequence.
%C Subsequence of A295078.
%C Numbers n such that A020639(n) = A020639(sigma(n)).
%C Numbers n such that A020639(n) = A071189(n).
%e 30 = 2*3*5 and sigma(30) = 72 = 2^3*3^2 hence 30 is in the sequence.
%p select(t -> min(numtheory:-factorset(t))=min(numtheory:-factorset(numtheory:-sigma(t))), [$2..1000]); # _Robert Israel_, Nov 14 2017
%t Rest@ Select[Range@ 150, SameQ @@ Map[FactorInteger[#][[1, 1]] &, {#, DivisorSigma[1, #]}] &] (* _Michael De Vlieger_, Nov 13 2017 *)
%o (Magma) [n: n in [2..1000000] | Minimum(PrimeDivisors(SumOfDivisors(n))) eq Minimum(PrimeDivisors(n))]
%o (PARI) isok(n) = factor(n)[1,1] == factor(sigma(n))[1,1]; \\ _Michel Marcus_, Nov 14 2017
%Y Cf. A000203, A020639, A071189, A088829, A295078.
%Y Cf. A071834 (numbers n such that n and sigma(n) have the same largest prime factor).
%K nonn
%O 1,1
%A _Jaroslav Krizek_, Nov 13 2017
%E Added n>1 to definition - _N. J. A. Sloane_, Feb 03 2018
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