

A145172


Number of pentagonal numbers needed to represent n with greedy algorithm.


2



1, 2, 3, 4, 1, 2, 3, 4, 5, 2, 3, 1, 2, 3, 4, 5, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 2, 3, 4, 5, 6, 3, 4, 2, 1, 2, 3, 4, 5, 2, 3, 4, 5, 6, 3, 4, 2, 3, 4, 5, 1, 2, 3, 4, 5, 2, 3, 4, 5, 6, 3, 4, 2, 3, 4, 5, 6, 3, 4, 1, 2, 3, 4, 5, 2, 3, 4, 5, 6, 3, 4, 2, 3, 4, 5, 6, 3, 4, 5, 6
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OFFSET

1,2


COMMENTS

Sequence is unbounded.


LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..10000


EXAMPLE

a(21)=6 since 21 = 12+5+1+1+1+1.


PROG

(PARI) a(n)={my(s=0); forstep(k=(sqrtint(24*n+1)+1)\6, 1, 1, my(t=k*(3*k1)/2); s+=n\t; n%=t); s} \\ Andrew Howroyd, Apr 21 2021


CROSSREFS

Cf. A000326 (pentagonal numbers), A053610, A057945, A180447, A192988.
Sequence in context: A053344 A092196 A100878 * A338484 A338493 A280053
Adjacent sequences: A145169 A145170 A145171 * A145173 A145174 A145175


KEYWORD

nonn


AUTHOR

Christina Steffan (christina.steffan(AT)gmx.at), Oct 03 2008


EXTENSIONS

Terms a(41) and beyond from Andrew Howroyd, Apr 21 2021


STATUS

approved



