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A349940 Terms of A339863 that are congruent to 5 modulo 6: numbers k == 5 (mod 6) such that A005179(k-1) > A005179(k) < A005179(k+1) >A005179(k+2) < A005179(k+3). 1

%I #6 Dec 10 2021 11:16:10

%S 425,845,1265,1643,1925,2525,2873,3335,3395,3575,3683,3971,4163,4307,

%T 4343,4475,4613,4667,4805,5141,5285,5423,5603,5945,6095,6305,6683,

%U 6851,6875,6893,6923,7337,7661,7733,7973,8075,8303,8393,8453,8723,8825,9191,9425,9581,9821,9875

%N Terms of A339863 that are congruent to 5 modulo 6: numbers k == 5 (mod 6) such that A005179(k-1) > A005179(k) < A005179(k+1) >A005179(k+2) < A005179(k+3).

%C Numbers k such that both k and k+2 are in A349939.

%C Numbers k == 5 (mod 6) such that, the smallest number with exactly k divisors is smaller than the smallest number with exactly k-1 or k+1 divisors, and that the smallest number with exactly k+2 divisors is smaller than the smallest number with exactly k+1 or k+3 divisors.

%e The smallest numbers with exactly 424, 425, 426, 427 and 428 divisors are 472877960873902080, 3317760000, 53126622932283508654080, 840479776858391445504 and 1216944576219100225436835077160960 respectively. The smallest number with exactly 425 divisors is smaller than the smallest number with exactly 424 or 426 divisors, the smallest number with exactly 427 divisors is smaller than the smallest number with exactly 426 or 428 divisors, and 425 == 5 (mod 6), so 425 is a term.

%o (PARI) isA349940(k) = if(k%6==5, my(v=vector(5, n, A005179(k-2+n))); v[2]<v[1] && v[2]<v[3] && v[4]<v[3] && v[4]<v[5], 0) \\ See A005179 for its program

%Y Cf. A005179, A339863, A349939.

%K nonn

%O 1,1

%A _Jianing Song_, Dec 05 2021

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Last modified December 7 01:49 EST 2023. Contains 367616 sequences. (Running on oeis4.)