A275535 a(n) = the smallest positive multiple of n that is the sum of more than 1 consecutive positive integers.

3, 6, 3, 12, 5, 6, 7, 24, 9, 10, 11, 12, 13, 14, 15, 48, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 96, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 192, 65, 66, 67

Offset

1,1

Comments

Surprisingly, first 14 terms coincide with A160899(1)..A160899(14).

Links

Table of n, a(n) for n=1..67.

Formula

a(n) = 3*n if n is a power of 2, a(n) = n else. - Alois P. Heinz, Aug 01 2016

Example

n=1, 3=1+2; n=2, 6 = 1 + 2 + 3; n=3, 3 = 1 + 2; n=4, 12 = 3 + 4 + 5;
n=5, 5=2+3; n=6, 6=1+2+3; n=7, 7=3+4; n=8, 24=7+ 8+ 9;
n=9, 9=4+5; n=10, 10=1+2+3+4; n=11, 11=5+6; n=12, 12=3+4+5;
n=13, 13=6+7; n=14, 14=2+3+4+5; n=15, 15=7+8.

Maple

a:= n-> `if`(2^ilog2(n)=n, 3*n, n):
seq(a(n), n=1..70);  # Alois P. Heinz, Aug 01 2016

Prog

(PARI) a(n)=if(n>>valuation(n, 2)==1, 3*n, n) \\ Charles R Greathouse IV, Aug 01 2016

Crossrefs

Cf. A138591, A160899.

Sequence in context: A120906 A258758 A210201 * A160899 A360981 A336769

Adjacent sequences: A275532 A275533 A275534 * A275536 A275537 A275538

Keyword

nonn,easy

Author

Zak Seidov, Aug 01 2016

Extensions

More terms from Alois P. Heinz, Aug 01 2016

Status

approved