The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A325619 Heinz numbers of integer partitions whose reciprocal factorial sum is 1. 7
 2, 9, 375, 15625 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k). The reciprocal factorial sum of an integer partition (y_1,...,y_k) is 1/y_1! + ... + 1/y_k!. LINKS FORMULA Contains prime(n)^(n!) for all n > 0, including 191581231380566414401 for n = 4. EXAMPLE The sequence of terms together with their prime indices begins: 1: {} 2: {1} 9: {2,2} 375: {2,3,3,3} 15625: {3,3,3,3,3,3} MATHEMATICA Select[Range[100000], Total[Cases[FactorInteger[#], {p_, k_}:>k/PrimePi[p]!]]==1&] CROSSREFS Factorial numbers: A000142, A007489, A022559, A064986, A108731, A115944, A284605, A325508, A325616. Reciprocal factorial sum: A002966, A051908, A316855, A325618, A325624. Sequence in context: A013169 A012991 A003818 * A049299 A024225 A266289 Adjacent sequences: A325616 A325617 A325618 * A325620 A325621 A325622 KEYWORD nonn,more AUTHOR Gus Wiseman, May 13 2019 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified March 31 06:14 EDT 2023. Contains 361634 sequences. (Running on oeis4.)