OFFSET
1,1
COMMENTS
REFERENCES
Richard P. Stanley, Enumerative Combinatorics, Volume 2, Cambridge University Press, 1999, p. 289.
LINKS
Gus Wiseman, Table of n, a(n) for n = 1..22485
Wikipedia, Durfee square.
EXAMPLE
The sequence of terms together with their prime indices begins:
125: {3,3,3}
175: {3,3,4}
245: {3,4,4}
250: {1,3,3,3}
275: {3,3,5}
325: {3,3,6}
343: {4,4,4}
350: {1,3,3,4}
375: {2,3,3,3}
385: {3,4,5}
425: {3,3,7}
455: {3,4,6}
475: {3,3,8}
490: {1,3,4,4}
500: {1,1,3,3,3}
525: {2,3,3,4}
539: {4,4,5}
550: {1,3,3,5}
575: {3,3,9}
595: {3,4,7}
MATHEMATICA
durf[n_]:=Length[Select[Range[PrimeOmega[n]], Reverse[Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]][[#]]>=#&]];
Select[Range[100], durf[#]>2&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Apr 12 2019
STATUS
approved