A098685
Numbers n such that pi(n) = sigma(d_1)*sigma(d_2)*...*sigma(d_k) where d_1 d_2 ... d_k is the decimal expansion of n.
Original entry on oeis.org
15, 155, 252, 916, 1189, 12654, 55293, 177554, 418634, 753248, 885193, 18252678, 18252687, 18469156, 18469165, 19882616, 19882623, 41867246, 73526936, 73526957, 233843449, 244895519, 2345784285, 2399877831, 4273447776, 29891923496, 42649454852, 728781494646
Offset: 1
885193 is in the sequence because pi(885193) = sigma(8)*sigma(8)*sigma(5)*sigma(1)*sigma(9)*sigma(3).
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Do[d=IntegerDigits[n];k=Length[d];If[ !MemberQ[d, 0]&&PrimePi[n]== Product[DivisorSigma[1, d[[j]]], {j, k}], Print[n]], {n, 10000000}]
A098684
Numbers n such that pi(n) = P(d_1!!)*P(d_2!!)*...*P(d_k!!) where d_1 d_2 ... d_k is the decimal expansion of n and P(i) is i-th prime.
Original entry on oeis.org
10, 30, 123, 41402, 1400523, 3173000, 3173001, 3173010, 3173011, 351226103, 351226113, 351226130, 351226131
Offset: 1
3173011 is in the sequence because pi(3173011)=P(3!!)*P(1!!)*P(7!!)*P(0!!)*P(1!!)*P(1!!).
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Do[d=IntegerDigits[n];k=Length[d];If[PrimePi[n]== Product[Prime[d[[j]]!! ], {j, k}], Print[n]], {n, 35000000}]
A110070
Numbers n such that n=pi(d_1!*d_2!*...*d_k!) where d_1 d_2 ... d_k is the decimal expansion of n.
Original entry on oeis.org
0, 3, 34, 52, 2800414
Offset: 1
2800414 is in the sequence because 2800414=pi(2!*8!*0!*0!*4!*1!*4!).
A160040
Numbers n such that pi(n) = prime(d_1)*prime(d_2)* ... *prime(d_k), where d_1, d_2, ... d_k is the decimal expansion of n, and the zeroth prime is 1.
Original entry on oeis.org
123, 2407, 5224, 8350, 11166, 30843, 51174, 66026, 172451, 202774, 266109, 546322, 1082682, 1830188, 1882036, 2754207, 3351809, 14355351, 23539612, 23539621, 24322837, 63950931, 122924349, 161485470, 204868903, 204868930, 252704792
Offset: 1
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c = 0; k = 1; lst = {}; fQ[n_] := ( c == Times @@ (IntegerDigits@ n /. {0 -> 1, 1 -> 2, 2 -> 3, 3 -> 5, 4 -> 7, 5 -> 11, 6 -> 13, 7 -> 17, 8 -> 19, 9 -> 23}) ); While[k < 6000000000, If[PrimeQ@k, c++, If[ fQ@k, AppendTo[lst, k]; Print@k]]; k++ ]; lst
Showing 1-4 of 4 results.
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