A139083 - OEIS

A139083

a(n) = (smallest prime-power among the largest powers of each prime dividing n) + (smallest prime-power among the largest powers of each prime dividing (n+1)).

3, 5, 7, 9, 7, 9, 15, 17, 11, 13, 14, 16, 15, 5, 19, 33, 19, 21, 23, 7, 5, 25, 26, 28, 27, 29, 31, 33, 31, 33, 63, 35, 5, 7, 9, 41, 39, 5, 8, 46, 43, 45, 47, 9, 7, 49, 50, 52, 51, 5, 7, 57, 55, 7, 12, 10, 5, 61, 62, 64, 63, 9, 71, 69, 7, 69, 71, 7, 5, 73, 79, 81, 75, 5, 7, 11, 9, 81

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OFFSET

1,1

COMMENTS

The largest powers of each prime dividing 44 are 2^2 and 11^1. The least of these is 2^2 =4. The largest powers of each prime dividing 45 are 3^2 and 5^1. The least of these is 5^1 = 5. So a(44) = 4 + 5 = 9.

LINKS

Table of n, a(n) for n=1..78.

FORMULA

a(n) = A034684(n) + A034684(n+1) [From Franklin T. Adams-Watters, Apr 09 2009]

PROG

Contribution from Franklin T. Adams-Watters, Apr 09 2009: (Start)

(PARI) minpp(n)=local(m, r, pp); if(n==1, 1, m=factor(n); r=m[1, 1]^m[1, 2]; for(i=2, matsize(m)[1], pp=m[i, 1]^m[i, 2]; if(pp<r, r=pp)); r)

vector(80, i, minpp(i)+minpp(i+1)) (End)

CROSSREFS

Cf. A139081, A139084.

Sequence in context: A140977 A161821 A317509 * A252002 A139081 A196189

Adjacent sequences: A139080 A139081 A139082 * A139084 A139085 A139086