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Minimal number of coins needed to pay n cents using coins of denominations 1 and 5 cents.
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%I #34 Nov 08 2022 08:07:08

%S 0,1,2,3,4,1,2,3,4,5,2,3,4,5,6,3,4,5,6,7,4,5,6,7,8,5,6,7,8,9,6,7,8,9,

%T 10,7,8,9,10,11,8,9,10,11,12,9,10,11,12,13,10,11,12,13,14,11,12,13,14,

%U 15,12,13,14,15,16,13,14,15,16,17,14,15,16,17,18,15,16

%N Minimal number of coins needed to pay n cents using coins of denominations 1 and 5 cents.

%C Sequence consists of runs of five consecutive integers: 0..4, 1..5, 2..6, 3..7, etc.

%H <a href="/index/Mag#change">Index entries for sequences related to making change.</a>

%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,1,-1).

%F Sum of quotient and remainder of n/5.

%F a(n) = A002266(n) + A010874(n).

%t Array[Total@ QuotientRemainder[#, 5] &, 77, 0] (* _Michael De Vlieger_, Nov 03 2022 *)

%o (PARI) a(n) = n\5 + n%5 \\ _Thomas Scheuerle_, Oct 24 2022

%o (PARI) a(n) = vecsum(divrem(n, 5)); \\ _Michel Marcus_, Nov 03 2022

%o (Python) def a(n): return n//5 + n%5 # _Michael S. Branicky_, Nov 03 2022

%Y Cf. A002266, A010874.

%Y Cf. A076314 (1,10 cents), A053344 (1,5,10,25 cents).

%K nonn,easy

%O 0,3

%A _Sandra Snan_, Oct 24 2022