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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 (list; graph; refs; listen; history; text; internal format)
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*k-1)/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

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Last modified December 4 09:10 EST 2021. Contains 349484 sequences. (Running on oeis4.)