78 = n * Prime(n) = 6*Prime(6)
78 = 12 + 3 × 4 + 5 × 6 + 7 + 8 + 9
78 = 9 + 8 + 7 × 6 + 5 + 4 × 3 + 2 × 1
78 = 0^6 + 1^7 + 2^9 − 3^8 + 4^0 + 5^5 + 6^1 + 7^4 + 8^3 + 9^2
78 = 2^2 + 5^2 + 7^2
785 = 225 + 355 + 485 + 585 + 615 + 645
78 = 111 − 11 × (1 + 1 + 1)
= 2 × 2 × (22 − 2) − 2
= 3 × 33 − 3
= 4 + (44 − 4 + 44)/4
= 5 × 5 + 55 − (5 + 5)/5
= 66 + 6 + 6
= 77 + 7/7
= 88 − (88 − 8)/8
= 9 × 9 − (9 + 9 + 9)/9
78 smallest number with 7 representations as a sum of 2 primes: 78 = 5 + 73 = 7 + 71 = 11 + 67 = 17 + 61 = 19 + 59 = 31 + 47 = 37 + 41
Number k such that k divides the sum of digits of all numbers from 1 to k.
a(n) = n^4 - n, n = 3
Sphenic number: Product of 3 distinct Primes, (List)
Factors: 1, 2, 3, 6, 13, 26, 39, 78
Seventy-eight
Representations, Binary to Hexadecimal:
1001110_2
2220_3
1032_4
303_5
210_6
141_7
116_8
86_9
71_11
66_12
60_13
58_14
53_15
4e_16
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