A325179 Heinz numbers of integer partitions such that the difference between the length of the minimal square containing and the maximal square contained in the Young diagram is 1.

3, 4, 6, 15, 18, 25, 27, 30, 45, 50, 75, 175, 245, 250, 343, 350, 375, 490, 525, 625, 686, 735, 875, 1029, 1225, 1715, 3773, 4802, 5929, 7203, 7546, 9317, 11319, 11858, 12005, 14641, 16807, 17787, 18634, 18865, 26411, 27951, 29282, 29645, 41503, 43923, 46585

Offset

1,1

Comments

The enumeration of these partitions by sum is given by A325181.

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

Links

Table of n, a(n) for n=1..47.

Gus Wiseman, Young diagrams for the first 32 terms.

Example

The sequence of terms together with their prime indices begins:
    3: {2}
    4: {1,1}
    6: {1,2}
   15: {2,3}
   18: {1,2,2}
   25: {3,3}
   27: {2,2,2}
   30: {1,2,3}
   45: {2,2,3}
   50: {1,3,3}
   75: {2,3,3}
  175: {3,3,4}
  245: {3,4,4}
  250: {1,3,3,3}
  343: {4,4,4}
  350: {1,3,3,4}
  375: {2,3,3,3}
  490: {1,3,4,4}
  525: {2,3,3,4}
  625: {3,3,3,3}

Mathematica

durf[n_]:=Length[Select[Range[PrimeOmega[n]], Reverse[Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]][[#]]>=#&]];
codurf[n_]:=If[n==1, 0, Max[PrimeOmega[n], PrimePi[FactorInteger[n][[-1, 1]]]]];
Select[Range[1000], codurf[#]-durf[#]==1&]

Crossrefs

Numbers k such that A263297(k) - A257990(k) = 1.

Positions of 1's in A325178.

Cf. A056239, A093641, A112798, A325180, A325181, A325192, A325196, A325198.

Sequence in context: A063477 A168219 A129827 * A308533 A369735 A322956

Adjacent sequences: A325176 A325177 A325178 * A325180 A325181 A325182

Keyword

nonn

Author

Gus Wiseman, Apr 08 2019

Status

approved