A326624 Heinz numbers of non-constant integer partitions whose geometric mean is an integer.

14, 42, 46, 57, 76, 106, 126, 161, 183, 185, 194, 196, 228, 230, 302, 371, 378, 393, 399, 412, 424, 454, 477, 515, 588, 622, 679, 684, 687, 722, 742, 781, 786, 838, 1057, 1064, 1077, 1082, 1115, 1134, 1150, 1157, 1159, 1219, 1244, 1272, 1322, 1563, 1589, 1654

Offset: 1

Author

Gus Wiseman, Jul 14 2019

Keywords

• nonn

Comments

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Examples

			The sequence of terms together with their prime indices begins:
    14: {1,4}
    42: {1,2,4}
    46: {1,9}
    57: {2,8}
    76: {1,1,8}
   106: {1,16}
   126: {1,2,2,4}
   161: {4,9}
   183: {2,18}
   185: {3,12}
   194: {1,25}
   196: {1,1,4,4}
   228: {1,1,2,8}
   230: {1,3,9}
   302: {1,36}
   371: {4,16}
   378: {1,2,2,2,4}
   393: {2,32}
   399: {2,4,8}
   412: {1,1,27}
		

Links

• Wikipedia, Geometric mean

Crossrefs

The case with prime powers is A326623.

Subsets whose geometric mean is an integer are A326027.

Cf. A001055, A067539, A078175, A102627, A316413, A326567/A326568, A326622, A326625.

Programs

Mathematica

primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[100],!PrimePowerQ[#]&&IntegerQ[GeometricMean[primeMS[#]]]&]